[Open Screen] Create a //discovery:public target

This creates a :public GN target for other Open Screen modules (or
embedders) to depend on.

It also:
- Consolidates the DNS-SD public APIs.
- Adds DEPS rules to enforce use of public headers.
- Adds DEPS rules to enforce layering inside of //discovery (with some
  exceptions).
- Adjusts deps for the //discovery targets.

Bug: b/179705382
Change-Id: Ice48b8d8937d3c68351d693b348a2928f14dfb4b
Reviewed-on: https://chromium-review.googlesource.com/c/openscreen/+/3032947
Commit-Queue: mark a. foltz <mfoltz@chromium.org>
Reviewed-by: Ryan Keane <rwkeane@google.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/BUILD.gn b/BUILD.gn
index 95ab0c96..7d26028a 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -16,7 +16,6 @@ group("gn_all") {
     "cast/sender:channel",
     "cast/streaming:receiver",
     "cast/streaming:sender",
-    "discovery:common",
     "discovery:dnssd",
     "discovery:mdns",
     "discovery:public",