Add .bb file extension for Babashka to Clojure

[not-in-stock]

Description

• Added new extension to Clojure group in lib/linguist/languages.yml
• Added a sample of Babashka code in samples/Clojure/tell-number.bb
• Added heuristic to make linguist distinguish between Babashka, BlitzBasic, and BitBake source files.

Checklist:

• I am associating a language with a new file extension.
  • The new extension is used in hundreds of repositories on GitHub.com
    • Search results for each extension:
      • https://github.com/search?utf8=%E2%9C%93&type=Code&ref=searchresults&q=extension%3Abb+defn+NOT+nothack
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • /pathom3-graphql/script/validate-and-format.bb
    • Sample license(s):
    • /pathom3-graphql/LICENSE
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

[lildude]

Sample source(s):

• tell-number.bb

You need to link to the actual source of the real-world sample file you have added, not the file within the Linguist PR 😁. We also need to know the license of the source file. Hint: that's what that section of the template that you deleted was for 😬.

The sample is also quite small which means it's not going to perform very well in circumstances where things slip past the heuristic. Please add at least one more sample, ideally a larger one (but not too large) that is more representative of the language.

[lildude]

A few tips to get the tests passing