Normalize action buttons placement

[luixxiul]

Move the button left of the input field.
Also replace Button with BrowserButton.

Fixes #10465

The margin between the buttons and the input field will be adjusted with another PR where I'm going to normalize siteDetails.less, so please ignore it for now.

Auditors:

Test Plan:

1. Open about:history
2. Open about:bookmarks
3. Make sure the action buttons are placed left of the input fields

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[cezaraugusto]

needs margin, history is looking like this for me:

[luixxiul]

Closing this PR for now. The commit to close #10465 will be cherry-picked by another PR later.