Reland "Use fastset for VRR modesetting"

This is a reland of commit 216d3120eaa516acf457a213b3e3d7df334cb33d

This change differs from the original by refactoring memory management
of the snapshots used by DisplayConfiguratorTest. The updated code
ensures that the cache will not contain references to freed snapshots,
which was previously the cause of msan failures which reverted the
original change.

Original change's description:
> Use fastset for VRR modesetting
>
> This change enforces the use of seamless modesetting for changes
> affecting the VRR_ENABLED crtc property, which has previously always
> allowed full modesets. Now that support for VRR fastsetting has been
> backported, it is not necessary to allow full modesets when changing
> the VRR_ENABLED state.
>
> This change also removes a workaround which required full modesetting
> to change the refresh rate throttling state whenever VRR_ENABLED was
> active. Now that the fix has been backported, seamless modesets can be
> used in this scenario.
>
> Bug: b:300915382
> Change-Id: I08538df9489cca6c04fa6af46f9fc15995cc0fdd
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4695533
> Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
> Commit-Queue: Andrew Wolfers <aswolfers@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1212192}

Bug: b:300915382
Change-Id: I5766aeaab9b8dea7786e709bcdf6299e30e1c261
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4982331
Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Commit-Queue: Andrew Wolfers <aswolfers@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1224480}