Merge generated tasks build configs to the base tasks automatically

[qianz2]

Task name:

Description:
BuildConfig merge: Add a function to make.js or BuildConfigGen to 'merge' a build config into the base task.
Merge all tasks in a build config to base tasks
e.g node make.js mergeBuildConfig --config Node20_225
This will 'merge' all tasks under build config Node20_225 into base tasks.

1. Copy generated task to base task, delete generated files in generated/Task[BuldConfig] folder and Tasks/taskname/_buildConfig/Node20_225 folder.
2. Update versionmap
3. Remove _buildConfigMapping section in task.json and task-loc.json
4. Delete the section in make-option.json.

Documentation changes required: (Y/N)

Added unit tests: (Y/N)

Attached related issue: (Y/N)

Checklist:

• Task version was bumped - please check instruction how to do it
• Checked that applied changes work as expected

[qianz2]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).