build: Port post-install script to Python

Avoid the whole shell/batch file shenanigans.
8 jobs for ebassi/for-master in 6 minutes and 9 seconds (queued for 1 second)
Status Job ID Name Coverage
  .Pre
passed #1243310
style-check-diff

00:00:45

 
  Build
passed #1243312
macos
macos

00:02:25

passed #1243311
meson-fedora-x86_64

00:05:28

passed #1243313
win32-ps
msys2-mingw64

00:01:59

passed #1243314
release-build

00:06:09

 
  Analysis
failed #1243316
asan allowed to fail
asan-build

00:01:38

passed #1243315
static-scan

00:02:57

 
  Docs
passed #1243317
reference

00:02:16

 
Name Stage Failure
failed
asan-build Analysis
 - conform+slow: 0 pass, 1 fail
Processing suite slow (units: 2)
- slow: 1 pass, 1 fail
Processing suite io (units: 7)
- io: 7 pass, 0 fail
Processing suite ops (units: 3)
- ops: 3 pass, 0 fail
Cleaning up file based variables
ERROR: Job failed: exit code 1