Implement Functionality to Restart R Within R-Instat

[N-thony]

Fixes partially #9308
@rdstern @jkmusyoka, this is a draft implementation of the functionality for restarting R within R-Instat. Please review and share your feedback.

[rdstern]

@N-thony this seems to work fine. I'm approving and expecting @Patowhiz to also check.
I tried to look at why you might want to do this and it seems that it largely to do with the way R uses memory.
This nicely completes the main tasks in the Tools menu. Should we now just get rid of the Run R Code and Save Current Options items? That could be a separate pull request.

[N-thony]

@N-thony this seems to work fine. I'm approving and expecting @Patowhiz to also check. I tried to look at why you might want to do this and it seems that it largely to do with the way R uses memory. This nicely completes the main tasks in the Tools menu. Should we now just get rid of the Run R Code and Save Current Options items? That could be a separate pull request.

@rdstern this is just a draft, I'm looking forward to replicate the RStudio restart system in R-Instat. The memory usage is increasing in this feature because this is not fully implemented.

What's Missing
To fully replicate a restart as in RStudio, the following aspects should be addressed:

1. Session-Level Restart:

• A complete R session restart requires tearing down and reinitializing the R process itself. The function currently clears the global environment but does not fully restart the underlying R process.

2. Unload and Reload Libraries:

• In RStudio, restarting a session unloads all loaded packages. This function does not handle unloading or reloading of R libraries, which could leave behind lingering dependencies or package states.

3. Startup Configuration:

• RStudio restarts with a clean environment, reloading any .Rprofile or startup scripts. The current function does not reinitialize such configurations.

4. Garbage Collection:

• The function does not explicitly trigger garbage collection before or after restarting, which might leave unused memory fragments.

5. Persistent Objects:

• Objects outside the global environment, such as options (options()) or temporary files, may still persist. These are typically reset in a full R session restart.

Once this is done, I think we will have a nice Restart system.

[N-thony]

@rdstern, I think this will work efficiently especially once we start using R-Instat packages developed by Lily.
I will get back to this once it fully implemented. Meanwhile I will try it out in a different branch offline with using R-Instat packages from our GitHub.

[rdstern]

@ChrisMarsh82 could you please also look at this one? It mirrors a facility in RStudio and we have asumed it in the Tools menu from the start. And maybe merge once you are ok?