[Param Update 1 of 2] Quoted string parameters in parameter files

[mabruzzo]

This should not be reviewed until after #492 has been merged

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This PR modifies Cholla so that all strings in the parameter files are quoted.

Important

This would be a backwards incompatible change. As such, I realize that it may take a long time to get merged (or it may be closed).

Motivation

If this PR is merged, Cholla's parameter files will be a strict subset of the TOML format. This has a few benefits:

1. Handling of whitespace in string values is no longer ambiguous.

2. We can start using an external TOML parsing library (there are a handful of nice C++ implementations that we can use simply by vendoring a single header file). This lets us get rid of the underlying parsing logic, and lets us fully use some of TOML's nice features (namely tables and arrays).

3. It will be possible to easily read the input parameter files with any valid TOML parsing library. This could be useful in analysis.

4. Relatedly, we could more easily programmatically modify Cholla input files (yeah, this is niche, but when it comes up, it's quite nice!)

What has changed

• This PR has made minimal internal changes to make this all work. I do think we should switch to an external TOML library, but I wanted to keep the diff minimal to make this PR.
• It also has tweaked the system-test logic to properly forward arguments
• It also introduces a python script that can be used to automatically update the legacy input files.
• Additionally, it includes updates to the documentation describing parameter files