feat(pkgbuilds): add anaconda dependencies packaging

Add PKGBUILD files for four Anaconda installer dependencies:
- pykickstart: Kickstart language parser (>= 3.73)
- python-blivet: Storage management abstraction layer
- python-productmd: OS product metadata parsers
- python-requests-file: file:// URL transport adapter for requests

These packages are required by rhinstaller but absent from Arch repos and AUR.
All use manual module installation to avoid unnecessary build dependencies.

Also fix .gitignore by removing pkgbuilds/ exclusion to allow tracking these new packages.

.gitignore

@@ -1,5 +1,4 @@
 out/
 local-repo/
 configs/baseline/airootfs/etc/systemd/system/multi-user.target.wants/
-configs/releng/airootfs/etc/systemd/system/multi-user.target.wants/
-pkgbuilds/
+configs/releng/airootfs/etc/systemd/system/multi-user.target.wants/