Core schema support and Typescript query planner redux (#622)

This commit re-introduces the TypeScript query planner, and adds support for core schema as input. This builds on the work @trevor-scheer has done in #588 to have composition output core schema instead of the previous incarnation of CSDL.

We've verified the output of the query planner through a large number of tests and feel confident these changes shouldn't affect the generated query plans.

@apollo/query-planner currently exposes the same API as before, but we'll change this in a follow-up PR to avoid repeated printing/parsing of schemas and queries.

Any references to CSDL both internally and outward facing have been updated to their new counterpart:
`supergraphSdl`. Supergraph SDL implements both the core and join specs, necessary for powering a router.

Co-authored-by: Trevor Scheer <trevor.scheer@gmail.com>
Co-authored-by: Jesse Rosenberger <git@jro.cc>

.github/workflows/lint.yml

@@ -59,9 +59,9 @@ jobs:
       ### BUILD CACHE ###
       - name: Cache Cargo registry, target, index
         uses: actions/cache@v2
-        id: cache-cargo
+        id: cache-cargo-v2
         env:
-          cache-name: cache-cargo
+          cache-name: cache-cargo-v2
         with:
           path: |
             ~/.cargo/registry

.github/workflows/rust-slow-test.yml

@@ -68,9 +68,9 @@ jobs:
       ### BUILD CACHE ###
       - name: Cache cargo registry, target, index
         uses: actions/cache@v2
-        id: cache-cargo
+        id: cache-cargo-v2
         env:
-          cache-name: cache-cargo
+          cache-name: cache-cargo-v2
         with:
           path: |
             ~/.cargo/registry

.github/workflows/rust-test.yml

@@ -67,9 +67,9 @@ jobs:
       ### BUILD CACHE ###
       - name: Cache cargo registry, target, index
         uses: actions/cache@v2
-        id: cache-cargo
+        id: cache-cargo-v2
         env:
-          cache-name: cache-cargo
+          cache-name: cache-cargo-v2
         with:
           path: |
             ~/.cargo/registry