Alternative to timezone_select()

[mavelo-llc]

Description
form_dropdown_timezone() supports all parameters of form_dropdown() and timezone-specific parameters.
timezone_select() in date_helper.php is too limited. Cannot specify field name or extra attributes.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[mergeable]

Hi there, mavelo-llc! 👋

Thank you for sending this PR!

We expect the following in all Pull Requests (PRs).

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• All git commits must be GPG-signed
• Must follow our style guide
• Be commented in the PHP source file
• Be documented in the user guide
• Be unit tested
• Pass all checks in GitHub Actions

Important

We expect all code changes or bug-fixes to be accompanied by one or more tests added to our test suite to prove the code works.

If pull requests do not comply with the above, they will likely be closed. Since we are a team of volunteers, we don't have any more time to work
on the framework than you do. Please make it as painless for your contributions to be included as possible.

See https://github.com/codeigniter4/CodeIgniter4/blob/develop/contributing/pull_request.md

Sincerely, the mergeable bot 🤖

[ddevsr]

Send new feature to branch 4.7