build: shard component e2e tests with bazel (#15078)

Currently running the e2e tests with Bazel takes about ~6 minutes. This is pretty slow in comparison to how fast the tests ran with our gulp setup.

In order to speed up the tests with Bazel by taking advantage of RBE's parallelism, we shard the e2e tests by creating a Bazel test target for each e2e spec file.

Author: devversion

e2e/BUILD.bazel

@@ -4,27 +4,43 @@ load("@angular//:index.bzl", "protractor_web_test_suite")
 load("//tools:defaults.bzl", "ts_library")
 
 ts_library(
-  name = "e2e_specs_lib",
-  srcs = glob(["**/*.ts"]),
+  name = "e2e_utils_lib",
+  srcs = glob(["util/**/*.ts"]),
   tsconfig = ":tsconfig.json",
   deps = [
     "@matdeps//@types/jasmine",
     "@matdeps//protractor"
   ]
 )
 
-protractor_web_test_suite(
-  name = "e2e",
+# For each spec file in the "components/" folder, we declare a Bazel target
+# that builds the JavaScript outputs for the e2e spec file.
+[ts_library(
+   name = "%s_specs_lib" % spec_file,
+   srcs = [spec_file],
+   tsconfig = ":tsconfig.json",
+   deps = [
+     "@matdeps//@types/jasmine",
+     "@matdeps//protractor",
+     ":e2e_utils_lib",
+   ]
+ ) for spec_file in glob(["components/**/*.spec.ts"])]
+
+# For each spec file in the "components/" folder, we declare a Protractor web test
+# suite target that runs the given e2e spec against the e2e-app devserver.
+[protractor_web_test_suite(
+  name = "%s_e2e" % spec_file,
   configuration = ":protractor.conf.js",
   on_prepare = ":start-devserver.js",
   server = "//src/e2e-app:devserver",
   deps = [
     "@matdeps//protractor",
-    ":e2e_specs_lib"
+    ":%s_specs_lib" % spec_file,
+    ":e2e_utils_lib",
   ],
   data = [
     "@angular//packages/bazel/src/protractor/utils",
     "//tools/axe-protractor",
   ],
-)
+) for spec_file in glob(["components/**/*.spec.ts"])]