sync: add pattern-based transfer ordering - #9766

What does this change do?

Adds pattern-based transfer ordering with syntax such as
--order-by 'pattern,*.tar.gz,*.md5'.

Patterns use rclone's existing filter-pattern parser. Files are ranked by the
first matching pattern, unmatched files come last, and full-path ordering makes
ties deterministic. Invalid or missing patterns fail during option parsing.
The documentation covers matching, tie behavior, and the comma limitation.

AI assistance disclosure: OpenAI Codex assisted with implementation and
verification. I read the repository's AI-assisted contribution guidance, ran
the checks below against current master, and take responsibility for the
submitted change.

Verification performed:

• go test -count=1 ./fs/filter ./fs/sync
• go vet ./fs/sync
• go test -race -count=10 -run TestNewLess ./fs/sync/
• make quicktest BUILD_SOURCEBRANCHNAME=order-by-patterns
• golangci-lint run ./... (v2.12.2, clean LF checkout): 0 issues
• CI-equivalent Markdown lint (markdownlint-cli2 v0.18.1): 0 errors
• Windows CLI copy with --check-first --transfers 1: observed
  a.tar.gz, b.tar.gz, a.md5, b.md5, notes.txt
• Windows CLI invalid-glob path: exit 7 with bad pattern glob

Linked issue

Fixes #3975

For new or changed backends

Not applicable; this changes sync ordering only.

Checklist

• This change is trivial OR it has been discussed and agreed in the linked issue.
• I have read the contribution guidelines.
• (If I used AI tools to help write this code) I have read and understood the AI-assisted contributions guidance, and I have tested and take ownership of this change myself.
• I have added tests for all changes in this PR if appropriate.
• I have added documentation for the changes if appropriate.
• All commit messages are in house style.
• (Backend changes only) Not applicable; this changes sync ordering only.
• This Pull Request is ready for review.