Make the release's Homebrew update survive changes Homebrew makes to the
cask, and fail visibly when it cannot: the step rebuilt gitx.rb by line
number, so one line added near its top produces a cask Ruby rejects,
and the job would still open the pull request with it.

- Move the update into scripts/update-homebrew-cask.sh, which replaces
  only the version and the two checksums, wherever they sit
- Fail the release job, leaving the cask alone, when those values are
  not each found exactly once, instead of sending a broken cask
- Keep the rest of the step order, the PR template and the PR as is

Give both Preferences tabs the same top and bottom margins that the
General and Updates tabs already have, and fix the Warnings list.

- Integration: add room above the Git Executable row, which sat against
  the toolbar, and balance the bottom margin.
- Warnings: add room above the description and below the Reset row.
- Warnings: reserve room for 4.5 rows and keep the tab at a fixed size,
  so the half visible row hints that the list scrolls once there are
  more dialogs. Drop the code that resized the list to the row count.
- Warnings: shorten the Force push description, which was cut off.
- Measured through accessibility, all four tabs now have 37 to 41 points
  above and below their controls.

Make the Warnings list react to clicks and Space, and let Tab leave it
in one press.

- Drop the delegate method that refused every row selection. The table
  tracks a click on a checkbox only when its row can be selected, so
  neither a click nor Space toggled anything.
- Make Tab and Shift-Tab leave the list at once. A cell-based table
  stopped on its checkbox column after the table itself, and its hidden
  scroller was a stop of its own, so it took several presses to get out.
- Add tests that click a checkbox, press Space on a selected row and
  press Tab in the list.

Move focus between the Preferences tabs with the arrow keys the way
Tab does, and turn Return into a click, so the focused tab reacts to
Space and Return.

- Left and Right put focus on an internal toolbar view that ignores
  Space. Step through the key view loop instead, which lands on the tab
  button itself.
- The tab button ignores Return and Enter, so click it for them.
- Checked with real key presses: Tab, Right and Left reach the tabs and
  Space or Return then shows the pane. No automated test, since the
  toolbar cannot be reached through the key view loop in the test run.

[UI] Fix a Read-Only 'Warnings' tabs and also fix Tab-order and behaviour

Co-authored-by: hannesa2 <[email protected]>

Pass the repository path to the shell as literal text, so a folder
name holding shell syntax is entered rather than evaluated.

- Single-quote the directory in the line sent to Terminal and iTerm2,
  escaping embedded single quotes; double quotes still expanded $(...)
  and backticks
- Test that the line quotes such a path, and that /bin/sh running it
  ends up in a directory named with $(...), backticks and quotes

Ported from hbmartin/gitx@7305c7db (the quoting only).

Remove zip from uploaded artifacts

Fix Open in Terminal running commands found in the repository path

Keep the Homebrew cask intact when its layout changes