Add Component Gallery to AGS

[victordibia]

This PR enables the addition of component galleries to a local instance of AutoGen Studio.
A gallery items is:

• a json file containing things
  • metadata .. description, author, url , date created etc....
  • component config item ... like teams, agents, termination conditions etc.
• Users can paste a url and we load it, drag it into the ui as a file, or paste it.
• Currently stored in localstorage (a future PR may make this an api endpoint)
• An imported gallery shows up in the teams section and also the component library .. users can drag and drop these conmponents into their teams!

Also fixes a bunch of other formatting and layout issues with AGS.

A default gallery is provided

and can be edited

are available for reuse while composing teams

Why are these changes needed?

This makes it really easy to create shareable gallery artifacts that either the AutoGen team or community can curate as examples, with components that can be composed and reused.

Related issue number

Closes #4203

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.