feat: parse the pr merge title and enforce conventional commits format

[daniel1302]

This PR allows to parse the PR title when PR is merged as merge commit.

PR merge commit looks like:

2a712b9cfd912f36b6f7f70d16b336575881881a
Merge pull request #6 from colegleason/add-q
fix(package.json): move q to dependancies since it is required to run
==END==

So We can shift first line of the body and use it as a subject.
Flag to enable this feature is --commit_body

There is also added flag --strict_conv_commits. If the flag is provided, commit messages must be in the format described in the Standard Document. If the commit message does not match the format, it is not assigned to the section.

There is example in Readme.

[rafinskipg]

Hi @daniel1302 looks good. I don't know if there's any blocker to release this. I think is ok. Can you also add your name to the contributors in the README and some explanation of this behavior in the documentation?

[daniel1302]

@rafinskipg I have added one more feature. And Description. If it is ok to merge it. I would be happy. I have added flags to provide backward-compatibility for people.