gh-140715: provide support for %F token in strptime; add test for it and %T

[jyalim]

Incrementally builds C99+ datetime support with addition of %F with single line of code. Also adds two tests: one for %F and another for previously supported %T.

Passed all tests (especially changes to new one).

Passed patchcheck.

• Issue: strptime token support and documentation modernization #140644

• Issue: Update str*time to C11 format codes #140715

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[StanFromIreland]

I moved this under #140715, can you please update the blurb filename.

[jyalim]

I moved this under #140715, can you please update the blurb filename.

I think this is done!

[StanFromIreland]

Please add them to this tuple:

cpython/Lib/test/test_time.py

Lines 361 to 363 in a2495ff

	for directive in ('a', 'A', 'b', 'B', 'c', 'd', 'H', 'I',
	'j', 'm', 'M', 'p', 'S',
	'U', 'w', 'W', 'x', 'X', 'y', 'Y', 'Z', '%'):

Also, please update the docs removing the (0) note from its row.

The implementation looks good, just a few small things and this will be ready :-)

[jyalim]

Thank you, @StanFromIreland, all changes have been made as requested!