finalization: step-*.sh: optionally skip `repo upload`

Teach the step-*.sh scripts to parse command line options. Add support
for --dry-run, which will skip the part where the CLs are uploaded:
useful for local experiments.

Bug: 323940469
Test: croot && build/tools/finalization/step-1.sh --dry-run # verify no CLs uploaded
Ignore-AOSP-first: VIC finalization happens outside AOSP
Change-Id: Ia58da02ae7a69c24f8332c90d1c779884e3a1dab