add reflex perf mode

[benedikt-bartscher]

add rx.Config (perf_mode) or env variable (REFLEX_PERF_MODE). Value should be an enum with warn, raise and ignore. Default should be warn, to avoid breaking changes.

warn: Warn about possible performance implications raise: raise Exception if performance issues are found ignore: do nothing, disable checks completely

iirc reflex currently only checks for state sizes. I would love to add another check for always dirty substates (caused by uncached vars).

[linear[bot]]

ENG-4119 add reflex perf mode

[benedikt-bartscher]

TODO: add socketio limit https://github.com/reflex-dev/reflex/pull/4392/files#r1851155673