✨ Inject location

[jortel]

Add support for injecting the source code path (to be analyzed) in the extension metadata. The Location field will continue to be injected. There are providers that do not honor the Location field but instead expect a workspaceFolders array populated. This is an inconsistency in providers. To support this, the location needs to be templated. A new location variable in the builtin namespace may be used by the extension writer.
Example:

metadata:
  provider:
    address: localhost:$(PORT)
    initConfig:
    - providerSpecificConfig:
        lspServerName: generic
        lspServerPath: /usr/local/bin/pylsp
        workspaceFolders:
        - $(builtin.location)                  <-------------- HERE
        dependencyFolders:
        - examples/python/__pycache__
        - examples/python/.venv
    name: python