Finalize status message strings to align with specs

Also describe them and make them translatable.

Bug: 407674931
Test: atest -c 'DocumentsUIGoogleTests:com.android.documentsui.JobPanelUiTest'
Flag: com.android.documentsui.flags.visual_signals_ro
Change-Id: I2b3920df4c753c6fade80215f540284f292a6387