refactor(compiler-cli): implement BabelAstFactory and AstHosts (#38866)

This commit adds the `AstHost` interface, along with implementations for
both Babel and TS.

It also implements the Babel vesion of the `AstFactory` interface, along
with a linker specific implementation of the `ImportGenerator` interface.

These classes will be used by the new "ng-linker" to transform prelinked
library code using a Babel plugin.

PR Close #38866

packages/compiler-cli/linker/BUILD.bazel

@@ -0,0 +1,18 @@
+load("//tools:defaults.bzl", "ts_library")
+
+package(default_visibility = ["//visibility:public"])
+
+ts_library(
+    name = "linker",
+    srcs = ["index.ts"] + glob([
+        "src/**/*.ts",
+    ]),
+    deps = [
+        "//packages/compiler-cli/src/ngtsc/translator",
+        "@npm//@babel/core",
+        "@npm//@babel/types",
+        "@npm//@types/babel__core",
+        "@npm//@types/babel__traverse",
+        "@npm//typescript",
+    ],
+)