Add `Rust/`-Lang Solutions

[dan-fritchman]

Adding a git submodule link to the Rust-lang solutions available at https://github.com/dan-fritchman/CtCI-6th-Edition-Rust.git.

Appreciate the work everyone here has done assembling these examples. Hope another language-worth of them can help.

Feedback welcome on the solutions themselves, whether you'd like to add the language, or anything else.

[navjotschahal]

Please raise an issue instead when the Macdowel team approves your request aka reviews and finds your fork from the issuue you opened . They will request for its ownership then you have to approve that again quating please refer MacDowel_instructions

[dan-fritchman]

Sorry for the delay here - got lost in the shuffle. This is now issue #251.