Support OAS's mutualTLS security option

[will-lauer]

OAS 3.1 added support for mutualTLS as a security option. Enable support for this with OAS definied APIs, allowing the query to select one of the configured client certificates.

Currently, OAS API document parsing fails if an OAS 3.1 definition is passed in. Support should be added for this so that APIs authenticated with mTLS (client certificates) can be supported using ARC's already exisitng certificate support.

[stale]

This issue has been automatically marked as stale because it has not had recent activity and is not currently prioritized. It will be closed in a week if no further activity occurs :)