Added MacOS startup item plugin

[Spferical]

One line description of pull request

Adds a parser for MacOS startup item plist files, a pre-launchd service mechanism.

Description:

Apple docs

Notes:

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One of the maintainers will examine your code, and may request changes. Check off the items below in order, and then a maintainer will review your code.

Checklist:

• [x] Automated checks (GitHub Actions, AppVeyor) pass
• [x] No new new dependencies are required or l2tdevtools has been updated
• [x] Reviewer assigned

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (04c3f1a) 86.04% compared to head (0e051cb) 86.05%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #4800 +/- ## ========================================== + Coverage 86.04% 86.05% +0.01% ========================================== Files 416 417 +1 Lines 37651 37678 +27 ========================================== + Hits 32396 32423 +27 Misses 5255 5255 ```

:umbrella: View full report in Codecov by Sentry.
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[Spferical]

Looks like a spurious docs build failure: 2024-02-06T04:37:51.7669893Z (sources/api/plaso.parsers.sqlite_plugins: line 4) broken https://hg.mozilla.org/mozilla-central/file/349a2f003529/netwerk/cookie/nsCookie.h - HTTPSConnectionPool(host='hg.mozilla.org', port=443): Max retries exceeded with url: /mozilla-central/file/349a2f003529/netwerk/cookie/nsCookie.h (Caused by SSLError(SSLEOFError(8, '[SSL: UNEXPECTED_EOF_WHILE_READING] EOF occurred in violation of protocol (_ssl.c:1007)')))

[joachimmetz]

Looks like a spurious docs build failure:

that happens from time to time, safe to ignore from your end. I'll try to review this PR later this week