Default to generating directory and package per data source, provider and resource

[bendbennett]

References: #20

The changes in this PR implement the following behaviour:

• If the --package flag is omitted when executing the generate command, a directory and package will be generated for each data source, provider and resource that is defined within the intermediate representation / spec.
• If the --package flag is included when executing the generate command, all generated code will be placed in the same directory and package.

Default Behaviour (--package flag omitted)

For example, if we have an intermediate representation / spec that defines the following data source, provider, and resource:

{
  "datasources": [
    {
      "name": "example",
      "schema": {}
    }
  ],
  "provider": {
    "name": "example",
    "schema": {}
  },
  "resources": [
    {
      "name": "example",
      "schema": {}
    }
  ]
}  

Executing the following generate command:

	go run ./cmd/terraform-plugin-codegen-framework generate all \
		--input ./internal/cmd/testdata/custom_and_external/ir.json \
		--output ./internal/cmd/testdata/custom_and_external/all_output/default_pkg_name

Generates the following output:

├── default_pkg_name
│   ├── datasource_example
│   │   └── example_data_source_gen.go
│   ├── provider_example
│   │   └── example_provider_gen.go
│   └── resource_example
│       └── example_resource_gen.go

The package within each of the three files is then:

package datasource_example

package provider_example

package resource_example

Package Specified (--package flag defined)

Conversely, if the same intermediate representation / spec illustrated above is passed to the generate command, and the --package flag is specified, for instance:

	go run ./cmd/terraform-plugin-codegen-framework generate all \
		--input ./internal/cmd/testdata/custom_and_external/ir.json \
		--package specified \
		--output ./internal/cmd/testdata/custom_and_external/all_output/specified_pkg_name

The following output is generated:

└── specified_pkg_name
    ├── example_data_source_gen.go
    ├── example_provider_gen.go
    └── example_resource_gen.go

The package in all three files is then:

package specified

[austinvalle]

lgtm 🚀

I imagine "naming collisions" will get a documentation section all to itself 😆

[austinvalle]

nice! 😎

[github-actions]

I'm going to lock this pull request because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active contributions.
If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.