[WIP] Add towncrier to manage CHANGELOG.md

[Ch3LL]

What does this PR do?

Add towncrier to help manage CHANGELOG.md

What issues does this PR fix or reference?

Fixes: #55836

Previous Behavior

Merge conflicts would occur anytime someone edits the changelog

New Behavior

no more merge conflicts and at release time we just need to run towncrier --version=3001 for example.

This PR require a contributor to create a new file under the changelog dir in the salt repo. The filename will need to be <issue number>.<type>. All given types are added, changed, deprecated, fixed, removed. Come release time we will run towncrier and this will combine all the files into the changelog and remove them.

Here is towncrier run with ---draft with these changes:

(salt)  ch3ll@thecakeisalie  ~/git/salt   towncrier  towncrier --draft --version=3001
Loading template...
Finding news fragments...
Rendering news fragments...
Draft only -- nothing has been written.
What is seen below is what would be written.

Salt 3001 (2020-04-14)
======================


Removed
-------

- test remove (#1234)


Deprecated
----------

- test deprecated (#1234)


Changed
-------

- test changed (#1234)


Fixed
-----

- test fixed (#1234)


Added
-----

- test added (#1234)

For the Sodium release we will have to do a combination of things. We will have to manually add the PRs we missed before this is added, and run this before the release for hte PRs that do use this.