Investigate sandboxed installer slowness #18550
Description
Ever since we upgraded to .NET 9/MSVC 2022 the sandboxed installers are extremely slow. We need to investigate and fix this before 1.16 beta can be released.
We suspect that the sandboxed installers are being problematic due to the concurrent installation enhancements spawning the modInstallerIPC module in very short intervals (especially now that we have the headless installation option), potentially not releasing the file handles quickly enough which is causing the binary itself to not be able to access its own path.
We're not able to remove the sandboxed installer variant due to potential security vulnerabilities when installing a CSharpScript mod variant which are common for FO3 and Oblivion.
The suggested solution is to have the installerIPC component run (lazily/on-demand) as a singleton instance whenever a CSharpScript mod is detected to maintain security for the users.
All other scripted mods will be run through a new native component as part of #18465 - this should still ensure performance/speed improvements for over 99% of the mods we would be installing.