DocsUI: Fix some resources for Material3

Some resources missed the call to getRes() and the m3 suffix.

Some resources were initialized statically so it didn't have a chance to
grab the right result from getRes(), so switch them to initialize at
constructor.

Bug: 403375773
Test: m DocumentsUIGoogle && manual inspection
Flag: com.android.documentsui.flags.use_material3
Change-Id: Ide68553a444cfe0e3b3256eb9800189eb19e31d0