Convert to {bslib}

[matt-dray]

The renal evidence map (source, deployment) uses {bslib} instead of {bs4Dash}. My opinion is that this app should also use {bslib}, it's more flexible and user-friendly.

As a result, this may address the following issues:

• UI: Potentially move navigation sidebar to top of page #55
• Content: Display data version in the app #51
• Bugs: Waffle briefly error messages #56
• Search: Only allow positive values in the string-distance input #44, Use discrete input for string distance #45, Improve lexical search #75