use default value for required arg if not provided

[pkbhowmick]

what

why

references

• DEV-2327

[osterman]

@pkbhowmick this PR is now in conflict

[osterman]

Please add something to this page: https://atmos.tools/core-concepts/custom-commands/

[osterman]

@coderabbitai can you suggest the changes to documentation related to this PR

[coderabbitai]

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@osterman, here's a suggestion for updating the documentation related to this PR:

Add a section to the Custom Commands documentation explaining that atmos now uses the default value for a required argument if it's not provided. This enhances flexibility when invoking custom commands.

For example, you could add:

### Default Values for Required Arguments

Atmos allows you to define default values for required arguments in your custom commands. If a required argument is not provided when the command is invoked, atmos will use the specified default value.

**Example:**

Given a custom command configuration:

```yaml
commands:
  deploy-stack:
    description: "Deploy a stack."
    arguments:
      - name: "environment"
        description: "The environment to deploy."
        required: true
        default: "dev"

You can now run:

atmos deploy-stack

Atmos will use "dev" as the default value for the environment argument.

This update will inform users about the new behavior introduced in this PR.