Change flags to use the newer definition style where the flag is read via a typed FlagHolder object returned by the DEFINE_... function. The advantage of doing this is that `flag.value` has a type known to the type checker, rather than reading it as an attr out of a gigantic config dictionary.
For jax.config flags, define a typed FlagHolder object that is returned when defining a flag, matching the ABSL API.
Move a number of flags into the file that consumes them. There's no reason we're defining every flag in `config.py`.
This PR does not change the similar "state" objects in `jax.config`. Changing those is for a future PR.
PiperOrigin-RevId: 551604974
* trailing-whitespace
* dangerous-default-value. None of these appear to be bugs in practice, but the potential for accidentally mutating the default value is there, and the cost of avoiding the problem is small.
* invalid-envvar-default. Pass strings as getenv() defaults.
* unnecessary-semicolon. Use tuples instead for this one-liner.
* invalid-hash-returned. Raise an exception rather than asserting false.
* pointless-string-statement. Use comments instead.
* unreachable. Use @unittest.skip() decorator rather than raising as first line in test.
* logging-not-lazy. Make the logging lazy.
* bad-format-string-type. Use f-string instead.
* subprocess-run-check. Pass check=...
PiperOrigin-RevId: 400858477
