show help messages when sub-command is run without required arguments

[viveksahu26]

Title:
Improve CLI UX: Show help text when sub-command is run without required arguments

Description:
Currently, when subcommands like edit are run without the required arguments, the CLI only displays a error like:

$ sbomasm edit
Error: accepts 1 arg(s), received 0

To help user with the command structure, we should automatically provide the help messages.

Desired Proposal

Update CLI behavior to automatically show help text when:

• A subcommand is invoked without required arguments
• -h or --help is passed
• No flags or args are provided after a subcommand

$ sbomasm edit
Error: requires at least 1 argument

Usage:
  sbomasm edit [flags]

Flags:
  -a, --append               append to field instead of replacing
      --author strings       author to add e.g 'name (email)'
      --copyright string     copyright to add e.g 'Copyright © 2024'
      --cpe string           cpe to add e.g 'cpe:2.3:a:microsoft:internet_explorer:8.*:sp?:*:*:*:*:*:*'
      --description string   description to add e.g 'this is a cool app'
      --hash strings         checksum to add e.g 'MD5 (hash'
  -h, --help                 help for edit
      --license strings      license to add e.g 'MIT'
      --lifecycle strings    lifecycle to add e.g 'build'
  -m, --missing              edit only missing fields
      --name string          name of the entity
  -o, --output string        path to edited sbom, defaults to stdout
      --purl string          purl to add e.g 'pkg:deb/debian/abc@1.0.0'
      --repository string    repository to add e.g 'github.com/interlynk-io/sbomasm'
      --search string        search string to find the entity
      --subject string       subject to edit (document, primary-component, component-name-version) (default "document")
      --supplier string      supplier to add e.g 'name (email)'
      --timestamp            add created-at timestamp
      --tool strings         tool to add e.g 'sbomasm (v1.0.0)'
      --type string          type to add e.g 'application'
      --version string       version of the entity

Global Flags:
  -d, --debug   debug output