fix: 445 `--lang` aliases

[Alex-ley-scrub]

@algora-pbc /claim #445

• test(apply): add simple stdin example from documentation as test case with an existing language and a language alias, which will fail until implemented
  • see #445
• fix(target_language): allow language aliases and extensions to be used and also map to the correct PatternLanguage
  • fixes #445

verified as fixed with (fails before PR commits succeeds after):

echo 'console.log(hello)' | cargo run -- apply '`hello` => `goodbye`' --stdin --lang=javascript

two test cases added to cover this in crates/cli_bin/tests/apply.rs which also verifies fix (fails before PR commits succeeds after - cargo test --test apply)

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[Alex-ley-scrub]

some screenshots

before:

echo 'console.log(hello)' | cargo run -- apply '`hello` => `goodbye`' --stdin --lang=javascript

after:

echo 'console.log(hello)' | cargo run -- apply '`hello` => `goodbye`' --stdin --lang=javascript

echo 'console.log(hello)' | cargo run -- apply '`hello` => `goodbye`' --stdin --lang=javascrip

[Alex-ley-scrub]

Hi @morgante - is there anything left for me to do before this can be merged? Thanks for your review, the final solution is pretty nice 👌