Add --package option to cfn submit for pre-built zip submission

[cv-dote]

Issue #, if available: #291

Description of changes:

Summary

Add a --package / -p option to cfn submit that uploads a pre-built schema handler package zip instead of building one from the current project. This enables common workflows such as building once (for example, inside a Docker container) and registering the same artifact across multiple regions, or registering a third-party zip without rebuilding.

Motivation

Today cfn submit tightly couples the packaging step with the upload step: the CLI always builds a zip from the current working directory and then uploads it. There is no way to feed in an already-built zip, so users can't:

• Build once, register in many regions.
• Register a vendor-built zip without rebuilding locally.
• Re-use the zip produced by cfn submit --dry-run.

Changes

Behavior

• Added --package <path> and -p <path> options to cfn submit.
• When --package is used, the CLI validates the zip, reads typeName and artifact_type from its .rpdk-config entry, and uploads the zip's bytes as-is.
• --package cannot be combined with --dry-run, --use-docker, or --no-docker (those flags configure the packaging step that --package skips). The CLI exits with a clear error if the user tries to combine them.
• The --package path does not read .rpdk-config from the current working directory, so the option works outside a CloudFormation CLI project.
• Because the zip does not carry a role template, --role-arn or --no-role must be specified together with --package.

When --package is not used, behavior is unchanged: the original packaging workflow runs with the same inputs, outputs, and log messages as before.

Code

Commit	Change
Add PackageValidator for pre-built zip submission	New src/rpdk/core/package_validator.py module that opens the zip, reads .rpdk-config, resolves artifact_type (with a RESOURCE fallback for legacy packages), asserts required entries, and logs cli-version from .cfn_metadata.json if present. All failures surface as InvalidProjectError.
Add Project.from_package classmethod for pre-built zip submission	New classmethod on Project that builds a minimal instance from the validator's output. Sets schema = {} so _upload's automatic-role branch stays inactive; the caller must provide --role-arn or --no-role. No existing methods are modified.
Add --package option to cfn submit	New _submit_existing_package helper and a single-branch dispatch in submit(). The flag-combination check runs before any I/O.
Add unit tests for --package submit workflow	New tests/test_submit.py covering parser, dispatch, flag conflicts, and end-to-end upload byte identity via a mocked _upload.
Document --package option in submit command	Updates to doc_source/resource-type-cli-submit.md (Synopsis, Options, Examples) and a one-line example in README.md.

Testing

• 19 new unit tests in tests/test_submit.py.
• 5 new unit tests in tests/test_project.py for Project.from_package.
• 17 new unit tests in tests/test_package_validator.py covering happy paths (RESOURCE / MODULE / HOOK), all validation error paths (missing path, non-zip, missing .rpdk-config, invalid JSON, unknown artifact_type, missing typeName, missing schema.json), the legacy RESOURCE fallback, and the best-effort metadata log.
• All pre-existing tests in tests/test_cli.py, tests/test_project.py, tests/test_package_validator.py, tests/test_submit.py, and tests/test_upload.py pass (206 tests).
• pre-commit (black, isort, flake8, pylint) passes. No new pylint warnings introduced; pylint rating unchanged at 9.98/10.

Example

# Build once.
cd ~/my-project
cfn submit --dry-run    # produces my-project.zip

# Register in multiple regions without rebuilding.
cfn submit --package ./my-project.zip --region us-east-1 --no-role
cfn submit --package ./my-project.zip --region ap-northeast-1 --role-arn arn:aws:iam::123456789012:role/MyExecutionRole

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.