When formatting with MD enabled, move selection inside ** or equivalent
When formatting with MD enabled, move selection inside ** or equivalent

Fixes https://github.com/vector-im/riot-web/issues/3225

Also insert `\n` after code-block and blockquote to fix https://github.com/vector-im/riot-web/issues/2746

aperezdc/matrix-react-sdk,aperezdc/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,aperezdc/matrix-react-sdk,matrix-org/matrix-react-sdk,aperezdc/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk