[roll] Roll third_party/pigweed pw_rpc: Build proto path arg list for Soong

For every .proto file in the Soong genrule to build a nanopb proto, add
its parent's parent's directory as a --proto-path argument to the
protobuf compiler. This allows genrules to have protos from different
sources. The requirement is that all sources to the same genrule are
prefixed once.

Test: Compiled prefixed proto with prefixed dependencies. Passes
  presubmits in Android main.
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/225031
Lint: Lint 🤖 <[email protected]>
Original-Revision: 74bc3cad816843c937e6faef722682ef321aded2
GitOrigin-RevId: 48f5fb2388e80f591218f81f397378f5a77d9789
Change-Id: I9fb4a6372c1a3d74a1ebd22e6973ba31a6e93e50

Author: Carlos Chinchilla

third_party/flower

@@ -492,7 +492,7 @@
              path="third_party/pigweed/src"
              remote="https://fuchsia.googlesource.com/third_party/pigweed.googlesource.com/pigweed/pigweed"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="dd2720f7c2a5222392035697d424bd835daa4cbe"/>
+             revision="74bc3cad816843c937e6faef722682ef321aded2"/>
     <project name="third_party/github.com/google/python_portpicker"
              gitsubmoduleof="fuchsia"
              path="third_party/python_portpicker/src"