[UX] Fix position of dialog header

[arielj]

This PR fixes #2609 by making all dialog headers static.

Also, now that we are not closing the dialogs when clicking outside (until we figure a solution for this #3194) it was sometimes annoying to have to scroll up to close a dialog.

dialog-haeder.mp4

This also fixes this issue with changelogs not having a height limit:

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Use the following Checklist if you have changed something on the Backend or Frontend:

• Tested the feature and it's working on a current and clean install.
• Tested the main App features and they are still working on a current and clean install. (Login, Install, Play, Uninstall, Move games, etc.)
• Created / Updated Tests (If necessary)
• Created / Updated documentation (If necessary)

[flavioislima]

good stuff