Add separate Post check for is_valid_body_field (#3263)

Add separate Post check for is_valid_body_field (#3263)

* Add separate Post check for is_valid_body_field

* Modify is_valid_body_check for posts only

* Fix check var reinit in validation.rs

* Extra empty line to rerun woodpecker with changes

* Change Option to bool, add false to non-post calls

* Woodpecker trick.. again

* Probable rust_fmt fail fixed

* cargo_clippy changes

* Missing space between = and if

* Remove ; after body length checks