Implement a basic benchmark test, and deprecate derivation.map()/flatMap()

This starts a new workspace at `packages/benchmarks` where future benchmarks
are going to sit. For now, it only contains a basic profile of a `sequence.play()`
setup.

It also removes all uses of `AbstractDerivation.map()/flatMap()` and uses prisms
instead.

package.json

@@ -10,6 +10,7 @@
   ],
   "scripts": {
     "playground": "yarn workspace playground run serve",
+    "benchmarks": "yarn workspace benchmarks run serve",
     "test:e2e": "yarn workspace playground run test",
     "test:e2e:ci": "yarn workspace playground run test:ci",
     "typecheck": "yarn run build:ts",