shellIntegration-rc.zsh: escape values in "E" (executed command) and "P" (property KV) codes

[rwe]

This implements the string escaping scheme documented for the "E" (executed) and "P" (property KV) codes. This is "pure" zsh and relies on no external utilities.

Although currently the only "required" escapes are backslash, semicolon, \a, and perhaps newlines, this conservatively escapes all non-alphanumeric characters.

Backslashes are doubled, non-alphanumerics are hex-escaped.

Sibling to:

• shellIntegration.fish: escape values in "E" (executed command) and "P" (property KV) codes #165631
• shellIntegration-bash.sh: escape values in "E" (executed command) and "P" (property KV) codes #165632
• shellIntegration.ps1: escape values in "E" (executed command) and "P" (property KV) codes #165634
• shellIntegrationAddon: fix broken deserializeMessage() implementation + add tests #165635

Relates to or resolves parts of:

• Shell integration: bash and zsh don't serialize \n and ; characters #157546
• Finalize shell integration sequences #155639

[rwe]

I've opened #165665 re the lint failure on the diagram comment.

The existing "hygiene" script apparently only permits the characters ┌└├ (omitting soft elbows, down-left connectors of any kind, and horizontal/vertical lines) 😑

These could be redone in ASCII, but with loss of legibility.

EDIT: The diagram is now ASCII-only.

[Tyriar]

Works great 👏

[rwe]

By the way, sorry for stomping on that review with the push! I usually rebase my unreviewed branches in bulk just to keep them current and if I don't notice a review beforehand it'll clobber. I'll look into updating my scripts to check for that in the last step, since reviewers also work in batches 😄 Done with that for now unless other change requests pop up.

[Tyriar]

No worries, that's best in my experience and what I do; don't force push after a review has occurred