pw_cpu_exception: Split facade

The pw_cpu_exception facade is comprised of three parts: the part
implemented by the architecture, and the part implemented by the
application, and some supporting libraries that make it easier to dump
CPU state. Since these are provided independently, the facade has been
split into three facades:

 1. entry
 2. handler
 3. support

Change-Id: I48c92f42b208f79596740f1bec59ed3d29e277a8
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/11646
Commit-Queue: Armando Montanez <amontanez@google.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>
diff --git a/pw_cpu_exception/BUILD b/pw_cpu_exception/BUILD
index 24e3a2a..d58a55c 100644
--- a/pw_cpu_exception/BUILD
+++ b/pw_cpu_exception/BUILD
@@ -19,6 +19,10 @@
 filegroup(
     name = "pw_cpu_exception",
     srcs = [
-        "public/pw_cpu_exception/cpu_exception.h",
+        "basic_handler.cc",
+        "public/pw_cpu_exception/entry.h",
+        "public/pw_cpu_exception/handler.h",
+        "public/pw_cpu_exception/support.h",
+        "start_exception_handler.cc",
     ],
 )