Update custom controls sample and migrate to new repo

[sascala]

Update custom controls sample and migrate to new repo

[snippet-bot]

Here is the summary of changes.

You are about to add 11 region tags.

• dist/samples/control-custom/app/index.html:7, tag maps_control_custom
• dist/samples/control-custom/app/index.ts:7, tag maps_control_custom
• dist/samples/control-custom/app/style.css:6, tag maps_control_custom
• dist/samples/control-custom/dist/index.html:7, tag maps_control_custom
• dist/samples/control-custom/docs/index.html:7, tag maps_control_custom
• dist/samples/control-custom/docs/index.js:6, tag maps_control_custom
• dist/samples/control-custom/docs/index.ts:7, tag maps_control_custom
• dist/samples/control-custom/docs/style.css:6, tag maps_control_custom
• samples/control-custom/index.html:7, tag maps_control_custom
• samples/control-custom/index.ts:7, tag maps_control_custom
• samples/control-custom/style.css:6, tag maps_control_custom

---

This comment is generated by snippet-bot.
If you find problems with this result, please file an issue at:
https://github.com/googleapis/repo-automation-bots/issues.
To update this comment, add snippet-bot:force-run label or use the checkbox below:

• Refresh this comment

[willum070]

Thank you so much, this totally makes my day!! A great start, but there are a few things to clean up. Specifically there's a refactor I'd like to see done for all migrations where it makes sense (see my comments and use #1119 for reference).

Also please make sure your PR doesn't contain any changes to dist/, as that stuff gets generated automatically once your changes are merged.

[willum070]

Here is where the fun begins! My practice has been to refactor things to be declarative rather than generate UI programmatically. Here are the steps I'd recommend:

• Take the CSS definitions from the createCenterControl() function and move them into a new CSS style.
• Nest the button element in the gmp-map element and use the slot attribute to position it.
• Within initMap(), add code to get the button element from the HTML.
• Move the event handler for the button into initMap().
• Remove the createCenterControl() function.
• Remove the injection code on ln. 61 - ln. 68, as it's not needed now that you've got HTML.

See #1119 for reference.