gh-118761: Improve import time of sqlite3

[Wulian233]

Improve import time of sqlite3 by around 2 times

Benchmark on Windows10, Python official 3.13.1

D:\Python313>hyperfine --warmup 8 "./python -c 'from sqlite3 import *'" "./python -c 'from sqlite3_new import *'"
Benchmark 1: ./python -c 'from sqlite3 import *'
  Time (mean ± σ):     135.0 µs ± 174.7 µs    [User: 1743.5 µs, System: 2196.8 µs]
  Range (min … max):     0.0 µs … 1225.1 µs    404 runs

Benchmark 2: ./python -c 'from sqlite3_new import *'
  Time (mean ± σ):     153.7 µs ± 196.7 µs    [User: 1868.9 µs, System: 1971.3 µs]
  Range (min … max):     0.0 µs … 2125.8 µs    409 runs

Summary
  ./python -c 'from sqlite3 import *' ran
    1.14 ± 2.07 times faster than ./python -c 'from sqlite3_new import *'

• Issue: Improve import time of various stdlib modules #118761

[erlend-aasland]

Please leave out all unrelated comment changes.

[AA-Turner]

It may be worth adding comments to indicate why we do the lazy imports -- but optional.

A

[ghost]

All commit authors signed the Contributor License Agreement.

[Wulian233]

All commit authors signed the Contributor License Agreement.

All the suggestion comments have been added, and this one appears because I have logged in to the wrong git account

[Wulian233]

@erlend-aasland I just realized today that I accidentally deleted an unmerged branch last month, which resulted in closing this PR. My apologies for the oversight. I've now recreated the pull request - the content remains exactly the same as before. Appreciate your understanding

#131796