NativeFS: Update dialog, icon, and tooltip string resources

Update the strings in accordance with the latest UX specs.
Remove bold emphasis in omnibox usage bubbles (keep it for prompts).
Update screenshots and sha1 files.

Consolidate IDS_NATIVE_FILE_SYSTEM_WRITE_PERMISSION_*_TITLE
Remove now unused |NativeFileSystemPermissionView::is_directory_|.

See updated screenshots in the associated bugs.

Bug: 995897, 996336
Change-Id: I0063b80e2a0fa4fe1442b90029011016d2d808b4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1764267
Reviewed-by: Marijn Kruisselbrink <[email protected]>
Commit-Queue: Michael Wasserman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#689506}
26 files changed