[Feature] openbb-platform-api: Add column header tooltips and templates.json route.

[deeleeramone]

1. Why?:

   • Updating the openbb-platform-api package to include hover readout for table column headers, and to add a route for templates.json

2. What?:

   • For Workspace tables, all field descriptions will now display on hover.
   • templates.json is served from a local file, ~/OpenBBUserData/workspace_templates.json
     • If the file does not exist, an empty JSON will be generated.
     • Add exported dashboard templates to the list in that file.

3. Impact:

   • Improved UX.
   • Ability to use the custom templates functionality with the Platform backend.

4. Testing Done:

   • Test by launching via, openbb-api