chore: render code style clean and update

[Koooooo-7]

Summary

Clean and make the compiler.js slimmer to main core compile logic, remove unnecessary code.

Changes:

• Move heading compiler to separate file like other renderer customizers.
• Move compileMedia as individual file also.
• Move the _renderTo to dom utils method.
• Remove the unused headline.js file.

Related issue, if any:

What kind of change does this PR introduce?

Code style update

For any code change,

• [x] Related documentation has been updated, if needed
• [x] Related tests have been added or updated, if needed

Does this PR introduce a breaking change?

Yes

No

Tested in the following browsers:

• [x] Chrome
• [ ] Firefox
• [ ] Safari
• [ ] Edge

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Name	Status	Preview	Comments	Updated (UTC)
docsify-preview	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 10, 2024 7:33am

[Koooooo-7]

--- Hi @trusktr Joe, thx for the review, already updated, PTAL.