Add Quint Specification language

[beu5a]

Description

This pull request adds support for the Quint specification language. Quint is a modern and executable specification language that is a particularly good fit for distributed and concurrent systems. It combines the robust theoretical basis of the Temporal Logic of Actions (TLA) with state-of-the-art type checking and development tooling. Quint has an active and growing ecosystem and is used widely in production.

• Main language repository: https://github.com/informalsystems/quint
• Non exhaustive list of use cases: https://quint.sh/docs/use-cases
• Grammar standalone repository: https://github.com/informalsystems/quint-grammars

Checklist:

• I am adding a new extension to a language.

• I am adding a new language.

  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension: The second query excludes the informalsystems organisation, which maintains the language, to make it easier to inspect usage outside of the maintaining organisation. Both queries show wide usage of the language across many repositories and users.
      • https://github.com/search?q=path%3A*.qnt+NOT+is%3Afork&type=code
      • https://github.com/search?q=path%3A*.qnt+NOT+is%3Afork+NOT+org%3Ainformalsystems&type=code
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/informalsystems/quint/blob/main/examples/classic/distributed/ClockSync/clockSync6.qnt
      • https://github.com/informalsystems/quint/blob/main/examples/classic/distributed/LamportMutex/LamportMutex.qnt
      • https://github.com/informalsystems/quint/blob/main/examples/classic/distributed/Paxos/Paxos.qnt
      • https://github.com/informalsystems/quint/blob/main/examples/solidity/ERC20/erc20.qnt
    • Sample license(s): Apache-2.0 (informalsystems/quint)
  • I have included a syntax highlighting grammar: https://github.com/informalsystems/quint-grammars
  • I have added a color
    • Hex value: #9d6ce5
    • Rationale: This color is central to the visual brand of the language and has been used for years across the project's logos and documentation: https://quint.sh/
  • I have updated the heuristics to distinguish my language from others using the same extension.

• I am fixing a misclassified language

• I am changing the source of a syntax highlighting grammar

• I am updating a grammar submodule

• I am adding new or changing current functionality

• I am changing the color associated with a language

[lildude]

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