Reasoner-validator

- Update Biolink Model Toolkit to 1.1.0 (implicit Biolink Model 3.5.0 update)

- Various tweaks to the case 'test edge' validation code, to meet SRI Testing needs
- Split BiolinkValidator class into two parent parts, for ease of lightweight BMT wrapping reuse; for case edge validation, also look at predicate children (bullet proof validation against None BMT handle?)
- Add trapi error code for missing knowledge graph; tweak Response validation codes and docs
- Guarantee return of the original seed identifier when getting the list of aliases from Node Normalizer

- Reversed order of codes in codes.yaml resulting in new documentation order: Critical at top, Information at the bottom
- Fixed bug with SemVer capture of local schema files: assume SemVer versioning is embedded in root file name
- Tiny tech debt clean up

- Introduced 'critical' category of validation messages (only a handful of messages to start, to be reviewed further)

- Bug fix for TRAPI Response sanitization