ST-1927: Use non gendered language

This is done by simple searching for the following regex:

(?<=\W|^)(he|she)(?=\W|$)/i -> they
(?<=\W|^)(his|her|hers)(?=\W|$)/i -> their, theirs
(?<=\W|^)(him|her)(?=\W|$)/i -> them
(?<=\W|^)(mr\.|ms\.|mrs\.)(?=\W|$)/i -> Mx.
(?<=\W|^)(man|woman)(?=\W|$)/i -> person
(?<=\W|^)(men|women)(?=\W|$)/i -> people

This MR also adds a CODEOWNERS file