Added BUILD file for gui2-fw-lib bazel build

This is another step along the way of having Native Bazel builds for Angular
Not fully there yet - waiting for Angular v9 in next 2 weeks
but don't want to wait that long to merge all of this

For most people the main concern is updates to WORKSPACE

Change-Id: I28170b8f8daaa2959327c259fe6a10df075113bb
diff --git a/BUILD b/BUILD
index 54c52d9..49aabfa 100644
--- a/BUILD
+++ b/BUILD
@@ -178,12 +178,25 @@
 
 buildifier(
     name = "buildifier_check",
-    exclude_patterns = ["./tools/build/bazel/generate_workspace.bzl"],
+    exclude_patterns = [
+        "./tools/build/bazel/generate_workspace.bzl",
+        "./web/gui2-fw-lib/node_modules/@angular/bazel/src/esm5.bzl",
+    ],
     mode = "check",
 )
 
 buildifier(
     name = "buildifier_fix",
-    exclude_patterns = ["./tools/build/bazel/generate_workspace.bzl"],
+    exclude_patterns = [
+        "./tools/build/bazel/generate_workspace.bzl",
+        "./web/gui2-fw-lib/node_modules/@angular/bazel/src/esm5.bzl",
+    ],
     mode = "fix",
 )
+
+# This export allows targets in other packages to reference files that live
+# in this package.
+# TODO Try to move this in to /web/gui2-fw-lib when possible
+exports_files([
+    "tsconfig.json",
+])