[issue41187] Convert the _msi module to Argument Clinic

[Serhiy Storchaka]

New submission from Serhiy Storchaka <storchaka+cpython at gmail.com>:

The proposed PR converts the _msi module to Argument Clinic.

* Fixes deprecation warnings with the "u" format.
* Adds signatures.
* Adds meaningful docstrings.

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components: Argument Clinic, Windows
messages: 372769
nosy: larry, paul.moore, serhiy.storchaka, steve.dower, tim.golden, zach.ware
priority: normal
severity: normal
status: open
title: Convert the _msi module to Argument Clinic
type: enhancement
versions: Python 3.10

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue41187>
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