feat: Show help when missing args for all cmds. (#209)

Update CLI handling for all commands to ensure help text is printed when no
arguments are provided. We did this inconsistently before, where it was
applied at the top level but not at any levels below that.

Signed-off-by: Andrew Lilley Brinker <alilleybrinker@gmail.com>

omnibor-cli/src/cli.rs

@@ -119,6 +119,7 @@ pub enum Command {
 }
 
 #[derive(Debug, clap::Args)]
+#[command(arg_required_else_help = true)]
 pub struct ArtifactArgs {
     #[clap(subcommand)]
     command: Option<ArtifactCommand>,
@@ -140,13 +141,15 @@ pub enum ArtifactCommand {
 }
 
 #[derive(Debug, Clone, clap::Args)]
+#[command(arg_required_else_help = true)]
 pub struct IdArgs {
     /// Path to identify
     #[arg(short = 'p', long = "path", help_heading = "Important Flags")]
     pub path: PathBuf,
 }
 
 #[derive(Debug, Clone, clap::Args)]
+#[command(arg_required_else_help = true)]
 pub struct FindArgs {
     /// Artifact ID to match
     #[arg(short = 'a', long = "aid", help_heading = "Important Flags")]
@@ -158,6 +161,7 @@ pub struct FindArgs {
 }
 
 #[derive(Debug, clap::Args)]
+#[command(arg_required_else_help = true)]
 pub struct ManifestArgs {
     #[clap(subcommand)]
     command: ManifestCommand,
@@ -180,12 +184,15 @@ pub enum ManifestCommand {
 }
 
 #[derive(Debug, clap::Args)]
+#[command(arg_required_else_help = true)]
 pub struct ManifestAddArgs {}
 
 #[derive(Debug, clap::Args)]
+#[command(arg_required_else_help = true)]
 pub struct ManifestRemoveArgs {}
 
 #[derive(Debug, clap::Args)]
+#[command(arg_required_else_help = true)]
 pub struct ManifestCreateArgs {
     /// Inputs to record in the manifest
     #[arg(short = 'i', long = "input", help_heading = "Important Flags")]
@@ -201,6 +208,7 @@ pub struct ManifestCreateArgs {
 }
 
 #[derive(Debug, clap::Args)]
+#[command(arg_required_else_help = true)]
 pub struct DebugArgs {
     #[clap(subcommand)]
     command: Option<DebugCommand>,