deprecate misleading cache flag from store

[amartin120]

Please check below, if the PR fulfills these requirements:

• Commit(s) and code follow the repositories guidelines.
• Test(s) have been added or updated to support these change(s).
• Doc(s) have been added or updated to support these change(s).

Associated Links:

• N/A

Types of Changes:

• Bug Fix

Proposed Changes:

• The --cache flag under hauler store was misleadingly left behind from a much earlier release before introducing cosign for image handling.

• Deprecating to stop confusion as it does absolutely nothing in the current versions of Hauler. Will remove completely at a later time.

Verification/Testing of Changes:

• Flag deprecated...

❯ hauler store --help 
Interact with hauler's embedded content store

Usage:
  hauler store [flags]
  hauler store [command]

Aliases:
  store, s

Available Commands:
  add         Add content to store
  copy        Copy all store contents to another OCI registry
  extract     Extract content from the store to disk
  info        Print out information about the store
  load        Load a content store from a store archive
  save        Save a content store to a store archive
  serve       Expose the content of a local store through an OCI compliant registry or file server
  sync        Sync content to the embedded content store

Flags:
      --cache string   (deprecated and currently not used)
  -h, --help           help for store
  -s, --store string   Location to create store at (default "store")

Global Flags:
  -l, --log-level string    (default "info")

Additional Context:

[dweomer]

LGTM (with minor question/concern)