[graphite] Use stable collection for static bindings

Since the layouts are passed by pointer in the `nextInChain` field,
their addresses need to stay valid until the BindGroupLayout is created.
With vector, if it ever grew, that would not remain the case. Since
there are usually only 0 to 1 immutable samplers, this likely never
happened (and also why it uses a built-in storage for 1).

Also removes the include for vector and uses TArray (we had been mixing
both throughout the file).

Bug: 520514458
Fixed: 523531719
Change-Id: I44c9566c68ab0e6c6d659ea77a423ddc50d53c76
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1264157
Reviewed-by: Thomas Smith <thomsmit@google.com>
Auto-Submit: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
(cherry picked from commit 6a4be3addd0a6e271e68a6a1bb873877e24813e9)
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1266376
Commit-Queue: Thomas Smith <thomsmit@google.com>