[DocsUI M3] Uplift layout and colours for files in the grid

Update the layout and colours of files in the grid to match the figma
spec. Simplify the layout by converting the unnecessary
MaterialCardViews to the simpler FrameLayouts.

Only the non-selected and selected state are handled. Future CLs will
implement focused, disabled, touch selected, etc.

See https://b.corp.google.com/issues/381962394#comment4 for before and
after screenshots.

Bug: 381962394
Test: m DocumentsUIGoogle && manual inspection
Flag: com.android.documentsui.flags.use_material3
Change-Id: Idac5968388ba37a559787e7db2230c10866a933f