Refactoring - Extract buttonRendering from main initToolbar()

[CloCkWeRX]

🤔Type of Request

• Bug fix
• New feature
• Improvement
• Documentation
• Other

🔗Resolves an issue?

While trying to simply reverse the display order of when columns vs search was appended to the DOM in initToolbar, I found it difficult as everything was appending to html.

Minor refactor to split out a specific sub rendering behaviour to its own thing - more could be done, just doing one chunk at a time.

📝Changelog

• Core
• Extensions

💡Example(s)?

☑️Self Check before Merge

⚠️ Please check all items below before reviewing. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• Changelog is provided or not needed

[djhvscf]

Please provide an Online Example to show this PR working, thanks!

[wenzhixin]

Hi @CloCkWeRX,

Thanks for this refactoring! I've created a similar PR (#8290) that includes the same extraction of renderButton from initToolbar, with one fix: the method call uses this.renderButton() instead of the bare renderButton() which would cause a ReferenceError.

That PR has been merged into develop, so I'll go ahead and close this one.

Thanks again for the initiative!