[MIGRATE] Split custom.py to separate files and folder for easier maintainability

[saifaldin14]

Note: This PR will be merged as a squash commit

---

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Related command

All az migrate commands, no change to the features this is just a reorganization of the code to be more maintainable and seperate.

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• Have you run azdev style <YOUR_EXT> locally? (pip install azdev required)
• Have you run python scripts/ci/test_index.py -q locally? (pip install wheel==0.30.0 required)
• My extension version conforms to the Extension version schema

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[azure-client-tools-bot-prd]

❌Azure CLI Extensions Breaking Change Test

❌migrate

rule	cmd_name	rule_message	suggest_message
❌ 1002 - CmdRemove	migrate local get-discovered-server	cmd migrate local get-discovered-server removed	please confirm cmd migrate local get-discovered-server removed
❌ 1006 - ParaAdd	migrate local replication init	cmd migrate local replication init added parameter resource_group	please remove parameter resource_group for cmd migrate local replication init
❌ 1007 - ParaRemove	migrate local replication init	cmd migrate local replication init removed parameter resource_group_name	please add back parameter resource_group_name for cmd migrate local replication init
❌ 1007 - ParaRemove	migrate local replication new	cmd migrate local replication new removed parameter resource_group_name	please add back parameter resource_group_name for cmd migrate local replication new
⚠️ 1001 - CmdAdd	migrate get-discovered-server	cmd migrate get-discovered-server added
⚠️ 1001 - CmdAdd	migrate local replication get-job	cmd migrate local replication get-job added
⚠️ 1006 - ParaAdd	migrate local replication new	cmd migrate local replication new added parameter resource_group
⚠️ 1001 - CmdAdd	migrate local replication remove	cmd migrate local replication remove added

[yonzhan]

Thank you for your contribution! We will review the pull request and get back to you soon.

[github-actions]

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[github-actions]

• For more info about extension versioning, please refer to Extension version schema

[Copilot]

Pull Request Overview

This PR reorganizes the Azure Migrate CLI extension codebase by splitting a large monolithic custom.py file into smaller, more maintainable modules organized in a hierarchical folder structure. The refactoring also adds two new commands (remove and get-job) and updates the extension version to 2.0.1b1 (preview).

Key changes:

• Splits helper functions from a single file into organized modules under helpers/ directory
• Updates all import paths throughout the codebase to reflect new structure
• Adds remove-local-server-replication and get-local-replication-job commands
• Marks extension as preview in metadata
• Cleans up unused exception variables in test code

Reviewed Changes

Copilot reviewed 24 out of 25 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
setup.py	Updates version to 2.0.1b1
azext_metadata.json	Marks extension as preview
custom.py	Updates imports to new helper module paths; adds new command functions
commands.py	Adds new command registrations; fixes command group hierarchy
_params.py	Updates argument context paths; adds parameters for new commands
_help.py	Adds help documentation for new commands
HISTORY.rst	Documents version changes
helpers/_utils.py	New consolidated utilities module
helpers/_server.py	Server discovery helper functions
helpers/replication/*/	Organized replication workflow modules
test_migrate_commands.py	Updates test mocks to new import paths; removes unused variables

Comments suppressed due to low confidence (1)

src/migrate/azext_migrate/helpers/replication/new/_process_inputs.py:1

• The function validate_server_parameters in _validate.py returns a tuple (rg_uri, machine_id) but in the old version in _process_inputs.py it only returned rg_uri. The function signature has changed during the refactoring. Ensure all call sites have been updated to handle both return values. The call in custom.py (line 281) correctly unpacks both values, which is good.