gh-102402: Fix floating point math issue by using time.time_ns() in logging.LogRecord

[dougthor42]

gh-102402: Fix floating point math issue by using time.time_ns() in logging.LogRecord.

• Adjust logging.LogRecord to use time.time_ns() instead of time.time().
• Change method of calculating LogRecord.msecs to be robust against floating point / binary representation arithmetic errors
• Added tests for the changes.

Notes / Open Questions:

1. LogRecord.msecs is a float so I kept it that way. Why is it a float even though it always has .0?
2. In order to minimize impact, I kept LogRecord.created as a float in seconds.
3. I didn't see any type annotations in logging.__init__ so I didn't add any for the new code. Would you like me to add some annotations?
4. I opted to use string manipulation to grab the msecs. I have an integer math-based approach, but it's, IMO, more verbose and harder to read/understand. LMK if you want me to switch back to that (there are still some minor fixes to apply to it).
   • I was able to come up with a math approach that is easy enough to understand.
5. I wasn't sure of the best place to put the tests, so I just built off the other msecs-related bug.

Fixes #102402.