Helpstyle: fix remaining inconsistent layout alignment and styling

[lioneil]

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This builds on #146.

Fixes various Help hints in the Main Menu dialog not inheriting the current theme's styling.

Sample: I'm using the same theme for both screenshot.

Before (help hint is supposed to be centered):

After the fix:

Before (Comic-Book theme, help hints are unstyled):

After:

There are other screens with the same issues: scraper menu, deeper down the custom collection submenus, the TextEdit dialogs, etc.

Hopefully this fixes all of them.

Note: I am not really a C++ developer, so you might see some poor choices I made in code.

[pjft]

Thanks for sending this over! Let me take a look at this and revert.

[pjft]

Thank you for putting this together. I tested it and it's working as intended.

Could you add it to the Edit Metadata window as well, and potentially squash everything into a single commit?

Any minor adjustments to the code - such as the comment I left regarding minor code style changes - can be applied in the same.

Thank you!