Extract raw shell/bash scripts as actual shell script files (#751)

### Description of the change

This is a preparation for #724 (bash script testing) which would be too complex to review if done there. I haven't changed the script contents.

### Benefits

Better IDE support, possibility for shell checks, tests.

### Possible drawbacks

-

### Additional information

I only extracted files that are native bash scripts. There are others, being a mix of Helm templating and shell scripts. Those scripts must be cleared first before extracting them as well.

Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/751
Co-authored-by: justusbunsi <sk.bunsenbrenner@gmail.com>
Co-committed-by: justusbunsi <sk.bunsenbrenner@gmail.com>

templates/gitea/init.yaml

@@ -7,11 +7,7 @@ metadata:
     {{- include "gitea.labels" . | nindent 4 }}
 type: Opaque
 stringData:
-  configure_gpg_environment.sh: |-
-    #!/usr/bin/env bash
-    set -eu
-
-    gpg --batch --import /raw/private.asc
+{{ (.Files.Glob "scripts/init-containers/init/*.sh").AsConfig | indent 2 }}
   init_directory_structure.sh: |-
     #!/usr/bin/env bash