Improve config modal

[JosephMarinier]

Description:

• Put loading and error states inside the Dialog box
  • Before, if there was an error, you would not be able to close de Dialog box, since the Xbutton wouldn't show up.
  • ⚠️ The diff in Settings.tsx seems overwhelming, but the code is just moving around, with no real changes.
• Render PageHeader in only one place (as opposed to once in BasicLayout and once in Exploration) so that the config modal stays in place if we use the browser back and forward buttons, to avoid losing unsaved changes in the config.
  • ⚠️ The diff in Exploration.tsx seems overwhelming, but it's just the indentation, with no real changes.
• Resolve warning
  • ⚠️ Not related to the config.

Checklist:

You should check all boxes before the PR is ready. If a box does not apply, check it to acknowledge it.

• ISSUE NUMBER. You linked the issue number (Ex: Resolve #XXX).
• PRE-COMMIT. You ran pre-commit on all commits, or else, you
  ran pre-commit run --all-files at the end.
• USER CHANGES. The changes are added to CHANGELOG.md and the documentation, if they impact
  our users.
• DEV CHANGES.
  • Update the documentation if this PR changes how to develop/launch on the app.
  • Update the README files and our wiki for any big design decisions, if relevant.
  • Add unit tests, docstrings, typing and comments for complex sections.

[nandhinibsn]

Changes looks good to me. 👍