Fix T80771: Avoid changing the visibility of loose geometry when entering Sculpt Mode

When entering scultp mode the visibility from the Face Sets is copied to
the base mesh. This steps was considering that if a vertex belongs to a
face with a visibible Face Set ID, it should be visible. As loose
geometry may not have any faces, those vertex were set to hidden.

Now this function check if a vertex visibility should be modified by the
face sets (by checking the loops), avoiding modifying the visibility of
loose geometry unintentionally.

Reviewed By: sergey

Maniphest Tasks: T80771

Differential Revision: https://developer.blender.org/D8899

Fix light rotation slider in Lookdev popover being disabled

Light rotation is supported both in world and view light orientation in
lookdev, so no reason to disable it.

Reviewed By: Blendify

Differential Revision: https://developer.blender.org/D8958

Unify all XYZ symmetry options using Mesh Symmetry

This adds XYZ symmetry as a property of meshes and updates all modes to
use the mesh symmetry by default to have a consistent tool behavior
between all modes and when switching objects.

Reviewed By: brecht, mano-wii, campbellbarton

Maniphest Tasks: T79785

Differential Revision: https://developer.blender.org/D8587

Object: Switch Object operator

This object operator exits and frees the edit data of the
current object and enters the same mode in another one in a single step,
without going through object mode or keeping multiple edit object data
active. It is assigned to the D key.

This solves all conflicts that the right/click select keymap and the
emulate 3 button mouse produces for this operation and it is independent
of the state of Lock object modes.
Also, as the SculptSession is freed, when using Multires objects go
back to their preview resolution level, so it is possible to work on
high vertex count scenes without slowing down the viewport and other
performance problems.

Reviewed By: #user_interface, pablovazquez

Differential Revision: https://developer.blender.org/D7510

Sculpt: Render Mask and Face Sets with modifiers active

This removes the limitation of the sculpt overlays not being visible
with modifiers active.

Reviewed By: fclem

Maniphest Tasks: T68900

Differential Revision: https://developer.blender.org/D8673

Overlay: Fade Inactive Geometry

This implements a new overlay that blends the bakground color over the
objects that are not in the same mode as the active object, making
them fade with the background.
This is especially needed for sculpt mode as there is no other overlay
or indication in the viewport to display which object is active.

This is intended to be used with D7510 in order to have a faster
workflow when sculpting models with multiple objects.

Reviewed By: fclem

Differential Revision: https://developer.blender.org/D8679

LookDev: Lock HDRI rotation to View

This adds an option for the HDRI rotation to follow the view rotation.
When this option is enabled, this allows EEVEE materials to be used as
matcaps for sculpting and painting.

This has an extra performance cost when orbiting around the model as the
lookdev cache needs to be recalculated, but in my test it is barely
noticeable.

Reviewed By: fclem

Differential Revision: https://developer.blender.org/D8566

Sculpt: Scale Cloth Filter

This filter scales the mesh as it was a softbody, producing folds in the
surface. The orientation of the folds can be controlled using the filter
axis and orientation.

This is an example of a cloth filter that uses deform coordinates instead
of forces, but probably it does not make much sense to expose it to the
user in a different way and with different parameters. I'll remove
FilterCache->enabled_force_axis in a later commit and use always
enabled_axis in SCULPT_filter_zero_disabled_axis_components
for both forces and deformation filters, so this function can also be used
in the mesh filter.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8661

Sculpt: Lower the default cloth deformation constraints strength

The deformation constraints strength were too strong and they were
preventing the cloth effects of the brushes with cloth deformation target
to create folds properly. This lowers the default, making the simulation
follow the deformation in a more relaxed way.

I'll make a separate patch to expose this as a property for certain brushes
and cloth deformers that may need higher values (like boundary with loop
falloff on a low poly mesh), but I think this default will work better for
most use cases.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8884

Fix T80771: Avoid changing the visibility of loose geometry when entering Sculpt Mode

When entering scultp mode the visibility from the Face Sets is copied to
the base mesh. This steps was considering that if a vertex belongs to a
face with a visibible Face Set ID, it should be visible. As loose
geometry may not have any faces, those vertex were set to hidden.

Now this function check if a vertex visibility should be modified by the
face sets (by checking the loops), avoiding modifying the visibility of
loose geometry unintentionally.

Reviewed By: sergey

Maniphest Tasks: T80771

Differential Revision: https://developer.blender.org/D8899