Prepare tooling for VMR initialization following the tarball generation

[premun]

Context

When we want to create the source build tarball, we start off in dotnet/installer and using some MSBuild targets we pull the sources of other repos and assemble the tarball that is then given to RedHat for consumption into their packaging system.

During this process, we generate some additional files, move files around and even remove some. Since the VMR will eventually replace the tarball, we need to bake this process into how we assemble the VMR.

Goal

For every step of the tarball generation process, we need to find a counterpart in the VMR. We also need to decide in which stage it will happen (be happening):

• Cloaking - Some will be part of the VMR configuration (e.g. removed files that we just won't sync)
• Initialization - Some steps will only happen once, when we initialize the VMR for the first time and will be part of the VMR (e.g. tarball/content copy)
• Every sync - Some will have to happen after every sync (e.g. git-info file creation)

Furthermore, we need to figure who will drive this process (Maestro, pipeline, ...?), where will the source code for this live. Lastly, we need to split what's outside of the VMR and what's inside (e.g. git synchronization will work the same across servicing branches as opposed to things dependent on local files inside the VMR).

Tarball generation steps

Step	Stage
Copy the tarball content	Initialization
Generate version files	Every sync
Create git-info files	Every sync
Remove unnecessary/forbidden files	Cloaking
Restore / copy text-only packages	Every sync
Handle source build patches	Initialization + Every sync

Breakdown of work

• Tooling for individual repo synchronization #10285
• Copy the tarball content #10266
• Generate version files #10265
• Create git-info files #10264
• Restore / copy text-only packages #10262
• Handle source build patches #10261
• Handle git submodules #10583
• Inline git submodules when ingesting individual repositories #10784