Rename Mathematica to Wolfram Language

[okofish]

Rename Mathematica to Wolfram Language, the current official name of the language used in Wolfram Research products.
Also, add .wls (Wolfram Language script) to the list of extensions.

Description

Disclosure: I am making this PR on behalf of my employer, Wolfram Research.
Mathematica, Wolfram Research's first product, originally had no distinct name for the language it implements, so that language came to be known de facto as "Mathematica" or the "Mathematica language". To rectify this, Wolfram introduced the "Wolfram Language" brand a little over 10 years ago; Wolfram Language (https://www.wolfram.com/language/) is the language implemented by multiple Wolfram products including Mathematica, Wolfram|One, and Wolfram Cloud. This PR attempts to reflect the current state of terminology by updating the language name in Linguist to "Wolfram Language".

There was a previous attempt to make the same change in 2020, but the PR (#4912) unfortunately got abandoned.
Some other relevant discussion and PRs: #3391, #5232

I also made two enhancements to the language spec.

• Add .wls (Wolfram Language script) extension: This extension is often used with WolframScript (https://www.wolfram.com/wolframscript/, https://reference.wolfram.com/language/ref/program/wolframscript.html), but can be used with other interpreters as well.
• Add exhaustive list of past and present interpreters: There are several names for WL interpreter binaries.
  • WolframKernel and wolfram are the current kernel binaries; MathKernel and math are the old (pre-rebranding) versions of these.
    • On GitHub: WolframKernel, MathKernel
  • WolframScript is a wrapper around the kernel intended for easy use in shebang scripts; MathematicaScript is the old version of this.
    • On GitHub: WolframScript, MathematicaScript
  • WolframNB is the Wolfram Language front-end (notebook UI) binary; Mathematica is the old version of this.
    • On GitHub: WolframNB, Mathematica

Checklist:

• I am adding a new extension to a language.
  • The new extension is used in hundreds of repositories on GitHub.com
    • Search results for each extension:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.wls+wolfram
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/WolframResearch/submit-paclet/blob/5b3122fe30ca4cc74c89a341ad5414b36c4cb4f3/src/install_dependencies.wls
      • https://github.com/WolframResearch/WolframLanguageForJupyter/blob/9a26ac78743cc47084c9c99ff75c5aee2657a409/configure-jupyter.wls
    • Sample license(s): MIT License
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

[lildude]

LGTM. Thanks.

Important

The changes in this PR will not appear on GitHub until the next release has been made and deployed. See here for more details.