Store fileserver

[amartin120]

Please check below, if the PR fulfills these requirements:

• The commit message follows the guidelines.
• Tests for the changes have been added (for bug fixes / features).
• Docs have been added / updated (for bug fixes / features).

What kind of change does this PR introduce?

• Currently, hauler store serve only supports serving an OCI compatible registry. This change implements an additional option to serve a traditional file server for files and charts that have been added to the local haul/store.

What is the current behavior?

• the hauler store serve command is only for serving a registry.

❯ hauler store serve -h   
Expose the content of a local store through an OCI compliant server

Usage:
  hauler store serve [flags]

Flags:
  -c, --config string      Path to a config file, will override all other configs
  -d, --daemon             Toggle serving as a daemon
      --directory string   Directory to use for registry backend (defaults to '$PWD/registry') (default "registry")
  -h, --help               help for serve
  -p, --port int           Port to listen on (default 5000)

Global Flags:
      --cache string       Location of where to store cache data (defaults to $XDG_CACHE_DIR/hauler)
  -l, --log-level string    (default "info")
  -s, --store string       Location to create store at (default "store") 

What is the new behavior (if this is a feature change)?

• added new subcommands for differentiating a registry or a file server.

❯ hauler store serve registry -h
Serve the embedded registry

Usage:
  hauler store serve registry [flags]

Flags:
  -c, --config string      Path to a config file, will override all other configs
      --directory string   Directory to use for backend.  Defaults to $PWD/registry (default "registry")
  -h, --help               help for registry
  -p, --port int           Port to listen on. (default 5000)

Global Flags:
      --cache string       Location of where to store cache data (defaults to $XDG_CACHE_DIR/hauler)
  -l, --log-level string    (default "info")
  -s, --store string       Location to create store at (default "store")

and

❯ hauler store serve fileserver -h 
Serve the file server

Usage:
  hauler store serve fileserver [flags]

Flags:
      --directory string   Directory to use for backend.  Defaults to $PWD/store-files (default "store-files")
  -h, --help               help for fileserver
  -p, --port int           Port to listen on. (default 8080)

Global Flags:
      --cache string       Location of where to store cache data (defaults to $XDG_CACHE_DIR/hauler)
  -l, --log-level string    (default "info")
  -s, --store string       Location to create store at (default "store")

Does this PR introduce a breaking change?

• hauler store serve no longer starts a registry without the added registry subcommand.

Other information: