Update source code `Kind` to `Type`. It's only changes within our code.
Changes to yaml tag (that will affect users) will be done in later PRs.
This is a breaking change since it updates telemetry's span attribute
from `source_kind` to `source_type`.
Related #817
Future updates will include:
* Updating a preprocessing function to convert config file from v1 to v2
* Update unmarshal function for ToolsFile to convert config file (test
will fail since the yaml tag is not yet updated).
* Update yaml tag (test will pass).
