Bring build scripts to AMBuild 2.2

[Kenzzer]

As requested by @sapphonie and other users in the SM discord, this PR aims at enabling ambuild 2.2 support for the buildscripts in this repository. Fix #11 and #10

Going over each file change :

AMBuildScript

This file follows a complete rewrite, I've mostly copied the buildscript i use in my own repositories. E.g ServerTools
The build script itself was mostly copied from SM repository, so there shouldn't be anything alien.

BreakpadSymbols
I've taken your work from SM repo, and pretty much backported it. The only thing I did not backport is upload_symbols.py as I simply look for it and execute it.

connect/buildbot/BreakpadSymbols

Line 4 in 2824a30

UPLOAD_SCRIPT = os.path.join(Extension.sm_root, 'tools', 'buildbot', 'upload_symbols.py')

I'm assuming this is alright, as extensions themselves can sometimes break compilation against newer SM codebase. So depending on a 3rd party buildscript should be fine ? Though if not desired, I'll simply bring it over in another commit.

PackageScript
I tried to limit the amount of changes I did to this file. Most of it is the same as before but I streamlined it.

Versioning
Mostly copied from SM repo, but changed so it generates the include files your extension looks for. I also have no idea how a Mercurial repository looks like, I'm too young, so I do not which file I've to make AMBuild depend upon so it triggers a regeneration of the version header, if the user switch commit/does change locally.
If the repo is instead git based, then it depends on the head file, much like Sourcemod.

generate_header.py - new file
I wrote this file by mixing the one from SM repo, and the python code I removed in Versioning so that it still generates in the same format the version file your extension requires. On that note, I also made it hybrid, so that whether the extension is built from the Mercurial repository, or the git repository, it still outputs something meaningful.

configure.py
Not much to say there, this is pretty much the standard configure python file every extension out there has. However do note the presence of --enable-auto-versioning, this a param I added so if someone attempts to build the extension, they by default will construct an extension with "Manual" as the version string.

AMBuilder
Pretty much the same file all extensions on the SM repo have, but instead with your extension source files.

product.version
I think this warrants a version bump 😄

The CI :

As requested by @asherkin, also added workflow that will build the extension for all the pull requests made on master. And if a push is made on the currently non existing action branch, the workflow uploads new releases of connect to https://builds.limetech.io/?p=connect
This was field tested on the private commits
https://github.com/Kenzzer/connect/actions/runs/4267733732/jobs/7429642982 & https://github.com/Kenzzer/connect/actions/runs/4267733732/jobs/7429643048

This requires the repo to setup two secret variables, USERNAME & PASSWORD which will be used for release uploads.

[sapphonie]

pog

[asherkin]

@sapphonie Just as a note, I've added the Actions secrets required for this.