Support standalone runtimes outside lune; fallback to uncolored print if runtime not found

[deviaze]

As discussed on the ROSS OSS discord, we can make the reporter somewhat more runtime-agnostic in the following manner:

"I'm thinking we extract an interface to generically define "print_color", then define the few colors frktest uses and pull out the implementation in separate _lune.luau and _seal.luau files? They can be conditionally required based on the detected runtime and if no runtime is found, fallback to just print without color?" - itsfrank

This would allow first-class support for other runtimes such as Zune and seal

[itsfrank]

I made the reporter generic in this branch: https://github.com/itsfrank/frktest/tree/generic-reporter

What is missing for seal support is the following:

1. Implement runtime detection for seal here:

   frktest/src/reporters/runtimes/get_runtime.luau

   Line 6 in cb2dade

   end

2. Implement seal's color function here:

   frktest/src/reporters/runtimes/color.luau

   Line 16 in cb2dade

   end

If you can just let me know how to achieve those with seal I can handle it and merge this into main

[itsfrank]

#8 was merged making the whole library platform-agnostic, now we just need to add seal color implementation

[itsfrank]

Feel free to open a PR adding seal as a supported runtime! Once you do, I can quickly follow-up with readme updates.

In addition to the 2 locations above, you can add a comment showing how to exit with non-0 code here:

frktest/examples/_run.luau

Line 29 in 3e9b3a6

-- require("@lune/process").exit(1)