Add Leo

[d0cd]

This PR adds Linguist support for the Leo progamming language. Leo is a high-level language that allows developers to use zero-knowledge proofs in their applications while abstracting away the cryptographic complexities. Leo programs are compiled into Aleo instructions, which can be executed on the Aleo blockchain.

References

• Leo
• Developer Documentation

Checklist

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on github.com. https://github.com/search?q=path%3A*main.leo+NOT+owner%3AProvableHQ++NOT+owner%3AAleoNet+NOT+is%3Afork&type=code&p=3. Note that the main.leo file is expected to occur once per repository, which meets the requirements outlined here.
  • I have included a real-world usage sample for all extensions added in this PR. They are covered under the license that is tagged at the top of each file.
  • I have included a syntax highlighting grammar: https://github.com/ProvableHQ/leo-linguist/blob/master/syntaxes/leo.tmLanguage.json
  • I have added a color
    • Hex value: #6814ec
    • Rationale: These are the brand colors.

[lildude]

This PR is missing the cached license file generated by this line in the add-grammar script:

linguist/script/add-grammar

Lines 133 to 134 in 39fd5e9

	log 'Caching grammar license'
	bundle exec licensed cache -c vendor/licenses/config.yml

Please add it.

[lildude]

The extension of the new language is used in hundreds of repositories on github.com. https://github.com/search?q=path%3A*main.leo+NOT+owner%3AProvableHQ++NOT+owner%3AAleoNet+NOT+is%3Afork&type=code&p=3. Note that the main.leo file is expected to occur once per repository, which meets the requirements outlined #5756.

This PR is not adding support for a single file, it's adding support for an extension which means the extension criteria applies and as with #6969, it appears quite common for a repo to contain multiple .leo files.

It seems quite common for .leo files to mention aleo so adding that to filter out files which clearly aren't Leo (there are a lot of XML files using this extension) indicates things are nearly there.

[DecimalTurn]

Closes #6900