Updates to Oncotree NCI/UMLS Mappings

[n1zea144]

We want start using our own manually curated NCI/UMLs mappings. With this in mind, we would like to:

• Disconnect integration with MSK crosswalk
• Inject our mapping files into the Oncotree backend for visualization on the website as is currently supported.

[sheridancbio]

The disconnection of crosswalk is now complete.

@ritikakundra : the current NCI/UMLS mappings for oncotree come from this static resource file: https://github.com/cBioPortal/oncotree/blob/master/core/src/main/resources/staticCrosswalkOncotreeMappings.txt

If there are updated NCI/UMLS mappings, they can be incorporated by making a PR to update that file. Format: first column: oncotree code second column: comma separated list of NCI codes third column comma separated list of UMLS codes

Aside from tab delimiter, no other spaces should be present.