Move prefix map to src

[gaurav]

Describe the bug
Almost all the files in the project/ directory are generated from the Biolink model files in src/ except for project/prefixmap/biolink_model_prefix_map.json, which appears to be edited manually.

To Reproduce
Check if biolink_model_prefix_map.json, a manually edited file, is in the project/prefixmap directory.

Expected behavior
All manually edited files should be in src/.

What working group (or team) did this request originate from?
N/A

Additional context
N/A

Tag relevant members for discussion
@sierra-moxon