Add bounding box option to data import tab

[cristinamullin]

Is your feature request related to a problem? Please describe.

User feedback from cybertown June 2025: "On the load tab, an option to search for data using coordinates could be useful (sounds like this may be possible in the future using a bounding box - cool!)"

Suggest to add options to input lat long extent manually, or to draw a box on a map and fill in the lat/long extent corresponding to the area selected on the map.

Describe alternatives you've considered

Alternatively, instead of a map, we could simply add input boxes so users can enter the lat/long extent manually.

Reminders for TADA contributors addressing this issue

New features and/or edits should include the following work:

• Create or edit the code.

• Document all code using line/inline and/or multi-line/block comments
  to describe what is does.

• Create or edit tests in tests/testthat folder to help prevent and/or
  troubleshoot potential future issues.

• If your code edits impact other functionality in the shiny
  app, ensure those are updated as well.

• Run styler::style_pkg(), devtools::document(), and devtools::check()
  and address any new notes or issues before creating a pull request.