Allow FSI evaluation option for FSharp.Formatting.

[kurtschelfthout]

Description

Add an option to do FSI evaluation to FAKE wrapper for FSharp.Formatting command-line tool.

TODO

Feel free to open the PR and ask for help

• New (API-)documentation for new features exist (Note: API-docs are enough, additional docs are in help/markdown)

• [] unit or integration test exists (or short reasoning why it doesn't make sense)

  Note: Consider using the CreateProcess API which can be tested more easily, see https://github.com/fsharp/FAKE/pull/2131/files#diff-4fb4a77e110fbbe8210205dfe022389b for an example (the changes in the DotNet.Testing.NUnit module)

• boy scout rule: "leave the code behind in a better state than you found it" (fix warnings, obsolete members or code-style in the places you worked in)

• [] (if new module) the module has been linked from the "Modules" menu, edit help/templates/template.cshtml, linking to the API-reference is fine.

• [] (if new module) the module is in the correct namespace

• [] (if new module) the module is added to Fake.sln (dotnet sln Fake.sln add src/app/Fake.*/Fake.*.fsproj)

• Fake 5 API guideline is honored

[matthid]

Adding new tests, similar to #2133 (note the switch to the CreateProcess API to be more testable) would be appreciated.

[jackfoxy]

I have a use for this. I hope it can move forward.

[matthid]

any interest in finishing this?

[jackfoxy]

@matthid is this just waiting on tests?
@kurtschelfthout

[matthid]

indeed

[jackfoxy]

I may be able to get to this in a couple weeks. (But I have no idea about what is involved.) I publicized this on twitter https://twitter.com/foxyjackfox/status/1064271460473090048