rust: apply more formatting fixes My cargo fmt updated these lines and they look good.

rust-utils: add normalize_case util to mirror Python one While we still don't handle filenames properly cross-platform, this at least sticks closer to the Python behavior. Differential Revision: https://phab.mercurial-scm.org/D6756

rust: fix warnings about trait objects without dyn being deprecated Differential Revision: https://phab.mercurial-scm.org/D6770

py3: convert hg executable path to bytes in missing case in procutil We (Google) noticed this in our tests when we use chg and a hg wrapper script not called 'hg'. The executable then ended up being a native string, which then failed in chgserver when trying to convert the environment dict to a byte string. Differential Revision: https://phab.mercurial-scm.org/D6775

py3: make statprof's chrome output work With this patch, this command works: python3 hg --profile --config profiling.statformat=chrome st (and it works with s/python3/python2/ as well) Differential Revision: https://phab.mercurial-scm.org/D6777

py3: for statprof's Chrome output, write json to string, then encode to bytes `json.dump(obj, fp)` requires `fp.write()` to accept str output, and since the file pointer we have there only accepts bytes, we need to change to json.dumps() and then encode as utf-8. We have already done the same thing for the json (non-Chrome) format in 4b7eb862692e (py3: encode json output to bytes and use write(), 2018-10-12). Differential Revision: https://phab.mercurial-scm.org/D6781

statprof: use context manager for file when writing flame graph Differential Revision: https://phab.mercurial-scm.org/D6780