[build] Overhaul Linux builds and refactor release workflow (#13997)

- Use `manylinux-shared` images for Linux builds
- Discontinue `yt-dlp_linux_armv7l`/`linux_armv7l_exe` release binary
- Add `yt-dlp_linux_armv7l.zip`/`linux_armv7l_dir` release binary
- Add `yt-dlp_musllinux` and `yt-dlp_musllinux_aarch64` release binaries
- Migrate `linux_exe` build strategy from staticx+musl to manylinux2014/glibc2.17
- Rewrite release.yml's "unholy bash monstrosity" as devscripts/setup_variables.py

Closes #10072, Closes #10630, Closes #10578, Closes #13976, Closes #13977, Closes #14106
Authored by: bashonly

devscripts/utils.py

@@ -1,5 +1,7 @@
 import argparse
+import datetime as dt
 import functools
+import re
 import subprocess
 
 
@@ -20,6 +22,23 @@ def read_version(fname='yt_dlp/version.py', varname='__version__'):
     return items[varname]
 
 
+def calculate_version(version=None, fname='yt_dlp/version.py'):
+    if version and '.' in version:
+        return version
+
+    revision = version
+    version = dt.datetime.now(dt.timezone.utc).strftime('%Y.%m.%d')
+
+    if revision:
+        assert re.fullmatch(r'[0-9]+', revision), 'Revision must be numeric'
+    else:
+        old_version = read_version(fname=fname).split('.')
+        if version.split('.') == old_version[:3]:
+            revision = str(int(([*old_version, 0])[3]) + 1)
+
+    return f'{version}.{revision}' if revision else version
+
+
 def get_filename_args(has_infile=False, default_outfile=None):
     parser = argparse.ArgumentParser()
     if has_infile: