v4.0.0: Add block support to post-message action and migrate to V1 (#10)

* Add block support to post-message action

* Remove post-message action tests

* Route post-message action through v1

* Inline post-message action runtime

* Trim post-message compatibility wording

* Require tagged chat IDs in post-message

v4: Add block support to post-message action and migrate to V1 (#10)

* Add block support to post-message action

* Remove post-message action tests

* Route post-message action through v1

* Inline post-message action runtime

* Trim post-message compatibility wording

* Require tagged chat IDs in post-message