partial fix: Added FormContextType and extending the F generic from it

[heath-freenome]

Reasons for making this change

• partial fix for Fix Typescript generics support in all themes in the beta #3072 by adding the new FormContextType and extending the F generic from it
• Updated @rjsf/utils to add the new FormContextType and update all types and functions to extend the F generic from it
• Updated @rjsf/core to update all uses of the F generic to extend FormContextType
• Updated the documentation around F accordingly
  • Also fixed an issue where the <S notation in Markdown caused strike-through formatting by changing it to \<S
• Updated the CHANGELOG.md accordingly

Checklist

• I'm updating documentation
  • I've checked the rendering of the Markdown text I've added
• I'm adding or updating code
  • I've added and/or updated tests. I've run npm run test:update to update snapshots, if needed.
  • I've updated docs if needed
  • I've updated the changelog with a description of the PR
• I'm adding a new feature
  • I've updated the playground with an example use of the feature