Use textContent to avoid HTML special characters in options

[ggorlen]

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Resolves https://github.com/processing/p5.js/issues/5778

Changes:

• Use textContent rather than innerHTML to set and compare options in a select menu, avoiding parsing HTML and escaping HTML special characters that might happen to be in the string (see linked issue for details).
• Add unit test with HTML special characters that fails on the old innerHTML and passes on textContent.

PR Checklist

• [x] npm run lint passes
• [x] Inline documentation is included / updated
• [x] Unit tests are included / updated