util: Add bls module

- Add functions for appending kernel parameters to the
Boot Loader Specification (BLS) as needed.

Signed-off-by: Renata Ravanelli <rravanel@redhat.com>

stages/org.osbuild.kernel-cmdline.bls-append

@@ -7,11 +7,11 @@ the tree or in a mount.
 """
 
 
-import glob
 import sys
 from urllib.parse import urlparse
 
 import osbuild.api
+from osbuild.util import bls
 
 SCHEMA_2 = r"""
 "options": {
@@ -60,24 +60,7 @@ def main(paths, tree, options):
 
     assert url.path.startswith("/")
     bootroot = root + url.path
-
-    # There is unlikely to be more than one bls config, but just
-    # in case we'll iterate over them.
-    entries = []
-    for entry in glob.glob(f"{bootroot}/loader/entries/*.conf"):
-        entries.append(entry)
-        # Read in the file and then append to the options line.
-        with open(entry, encoding="utf8") as f:
-            lines = f.read().splitlines()
-        with open(entry, "w", encoding="utf8") as f:
-            for line in lines:
-                if line.startswith('options '):
-                    f.write(f"{line} {' '.join(kopts)}\n")
-                else:
-                    f.write(f"{line}\n")
-    assert len(entries) != 0
-    print(f"Added {','.join(kopts)} to: {','.join(entries)}")
-    return 0
+    bls.options_append(bootroot, kopts)
 
 
 if __name__ == '__main__':