Update EEPs have more consistent header contents

[garazdawi]

As the headers in the EEPs are mostly freetext, the contents have diverged depending on author. This PR brings back some consistency and adds some checks so that it will not diverge more in the future.

The checks added are;

1. Erlang-Version must be in the format of an Erlang/OTP version tag and must be present if an EEP is in Final state.
2. Github actions actually check that the current checks are followed.