Removed all teaclave usages. Currently only check-enclave flow functions

[eladr7]

Notice that the repo has no query/execute functionalities. These should be implemented on the gramine side.

[Cashmaney]

From a quick overview -

1. Can you restore third_party/proto? It is used in multiple places
2. Can you add the gramine server to this repo? It will be easier to track if it's all in one place