docs(migration): add components migration docs (#9255)

* docs(migration): add components migration docs

* docs(migration): add additional info

* docs(migration): add docs for theme-tokens entrypoint

* docs(migration): add docs for _theme.scss entrypoint

* docs(migration): update docs for type and vars entrypoint

* docs(migration): update components section

* docs: update selector names in snippets

* docs(migration): update to include new import paths

* Update docs/migration/11.x-carbon-components.md

Co-authored-by: Andrea N. Cardona <[email protected]>

* Update docs/migration/v11.x.md

Co-authored-by: Andrea N. Cardona <[email protected]>

* chore(format): run prettier

Co-authored-by: Andrea N. Cardona <[email protected]>