Metadata apply CLI needs an import/incremental strategy

### Is your proposal related to a problem?

metadata apply currently replaces existing metadata. In the future, I can imagine a case where users will want to consume multiple existing patterns from other projects with a flow similar to `metadata apply action from existing-project`.

### Describe the solution you'd like

The ability to:
1. Define which project I want to apply metadata from
2. Define the path to which type of metadata I want to apply from that project (perhaps even which named item in that metadata)
3. Define the merge strategy (replace, add, merge) for the metadata getting applied
-- Nice to have ---
4. Ideally, define a remote source for the metadata from location.
5. If it was technically possible, define a remote source for the "to" location. Ie, apply Github sourced metadata to my Cloud repo via CLI. Allows for agencies to define custom features not privy to public consumption.