CMakeLists.txt — bgppplib library, bgppp_bin executable, and install targets

Summary:
Complete the CMakeLists.txt with the C++ library, binary, and install targets.

**bgppplib** — static library containing all OSS-eligible BGP++ source files (~85 .cpp files) organized by module: service layer, common utilities, config, adjrib, rib (including FibEbb), peer management (including VipPeerManager), policy (including base/ from A6), fsdb, nexthop tracking, change tracking, health, stats, watchdog, and the consolidated bgplib (fibers + coro + message parsing).

Files explicitly excluded (under /facebook or not OSS):
- facebook/MainBB.cpp — EBB binary entry point
- facebook/BuildInfo.cpp — internal BuildInfo (uses facebook::BuildInfo)
- facebook/ScubaLoggerFactory.cpp — scubadata dependency
- eos_wrapper/ — Arista EOS specific
- tests/ — deferred to follow-up diff

**bgppp_bin** — OSS binary entry point using MainOSS.cpp (from A1 D100714533). Installed as `bgppp` in sbin.

**Install targets** — headers (*.h) and thrift files (*.thrift) from neteng/, configerator/, and common/ directories.

Reviewed By: mloo3

Differential Revision: D103337797

fbshipit-source-id: 5a3b9610bb57f0ba942616d1997b71c7b07d632d

Author: induvsuresh

build/fbcode_builder/manifests/bgp

@@ -17,10 +17,12 @@ builder = nop
 [dependencies]
 boost
 fb303
+fboss
 fbthrift
 folly
 re2
 
 [shipit.pathmap]
 fbcode/neteng/fboss/bgp = neteng/fboss/bgp
 fbcode/neteng/fboss/bgp/public_tld = .
+fbcode/fboss/common = common