changelog workflow update

[MajorMoth]

About the PR

Updated the changelog script to use embeds and split changes per PR. It also uses embeds now, and adds the first image from every PR as a feature preview.

Why / Balance

April asked me to.

Technical details

Cleaned up the structure of the file, now there is a helperfunctions file, so that the code flows more logically and is easier to modify/reference.

Test plan

We will figure that one out.

Media

Example new changelog:

Requirements

• I have read and am following the Macrocosm Pull Request Conventions.
• I have tested this pull request and written instructions on how to test it.
• I have added media to this PR or it does not require an in-game showcase.

Licensing

• All code in this pull request can be licensed to MIT.
• (OPTIONAL) I give permission to seeing this feature upstreamed to Macrocosm in the future, but please wait until it gets tested for a little bit and we work out any issues.

Breaking changes

Moved all the changelog related files from Tools to their own subfolder in Tools/changelogs.
Fixed all the references to the files I found.

[MajorMoth]

this will need a bit of extra setup after merging (webhook url secret an stuff)

[sleepyyapril]

this will need a bit of extra setup after merging (webhook url secret an stuff)

we have existing vars for that!