[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

.github/workflows/release-nightly.yml

@@ -7,7 +7,7 @@ permissions:
 
 jobs:
   check_nightly:
-    if: vars.BUILD_NIGHTLY != ''
+    if: vars.BUILD_NIGHTLY
     runs-on: ubuntu-latest
     outputs:
       commit: ${{ steps.check_for_new_commits.outputs.commit }}
@@ -22,9 +22,13 @@ jobs:
             "yt_dlp/*.py"
             ':!yt_dlp/version.py'
             "bundle/*.py"
+            "bundle/docker/compose.yml"
+            "bundle/docker/linux/*"
             "pyproject.toml"
             "Makefile"
             ".github/workflows/build.yml"
+            ".github/workflows/release.yml"
+            ".github/workflows/release-nightly.yml"
           )
           echo "commit=$(git log --format=%H -1 --since="24 hours ago" -- "${relevant_files[@]}")" | tee "$GITHUB_OUTPUT"
 
@@ -34,17 +38,16 @@ jobs:
     uses: ./.github/workflows/release.yml
     with:
       prerelease: true
-      source: nightly
+      source: ${{ (github.repository != 'yt-dlp/yt-dlp' && vars.NIGHTLY_ARCHIVE_REPO) || 'nightly' }}
+      target: 'nightly'
     permissions:
       contents: write
-      packages: write  # For package cache
-      actions: write  # For cleaning up cache
       id-token: write  # mandatory for trusted publishing
     secrets: inherit
 
   publish_pypi:
     needs: [release]
-    if: vars.NIGHTLY_PYPI_PROJECT != ''
+    if: vars.NIGHTLY_PYPI_PROJECT
     runs-on: ubuntu-latest
     permissions:
       id-token: write  # mandatory for trusted publishing