Support namespace scoping for git config file

[isc-npetroce]

We should permit having a different embedded-git-config.json on a per-namespace level in order to play nicer with production decomposition, as customers might configure separate local repositories for each namespace and pull into a single remote. Currently we only support having a global config file for the entire repo.

[isc-pbarton]

For more context, this is to support a monorepo where code for different namespaces is mapped to different subdirectories.
For example, classes for namespace1 are mapped to /namespace1/cls/ and classes for namespace2 are mapped to /namespace2/cls/.

The current workaround to support this is to add embedded-git-config.json to .gitignore