Fix the package recipe for consumers of libxrpl (#4631)

- "Rename" the type `LedgerInfo` to `LedgerHeader` (but leave an alias
  for `LedgerInfo` to not yet disturb existing uses). Put it in its own
  public header, named after itself, so that it is more easily found.
- Move the type `Fees` and NFT serialization functions into public
  (installed) headers.
- Compile the XRPL and gRPC protocol buffers directly into `libxrpl` and
  install their headers. Fix the Conan recipe to correctly export these
  types.

Addresses change (2) in
https://github.com/XRPLF/XRPL-Standards/discussions/121.

For context: This work supports Clio's dependence on libxrpl. Clio is
just an example consumer. These changes should benefit all current and
future consumers.

---------

Co-authored-by: cyan317 <120398799+cindyyan317@users.noreply.github.com>
Signed-off-by: Manoj Doshi <mdoshi@ripple.com>

CMakeLists.txt

@@ -97,8 +97,8 @@ if (NOT USE_CONAN)
   include(deps/Rocksdb)
   include(deps/Nudb)
   include(deps/date)
-  include(deps/Protobuf)
-  include(deps/gRPC)
+  # include(deps/Protobuf)
+  # include(deps/gRPC)
   include(deps/cassandra)
   include(deps/Postgres)
   include(deps/WasmEdge)
@@ -129,8 +129,6 @@ else()
   endif()
   find_package(nudb REQUIRED)
   find_package(date REQUIRED)
-  include(conan/Protobuf)
-  include(conan/gRPC)
     if(TARGET nudb::core)
     set(nudb nudb::core)
   elseif(TARGET NuDB::nudb)
@@ -154,8 +152,8 @@ else()
     lz4::lz4
     OpenSSL::Crypto
     OpenSSL::SSL
-    Ripple::grpc_pbufs
-    Ripple::pbufs
+    # Ripple::grpc_pbufs
+    # Ripple::pbufs
     secp256k1::secp256k1
     soci::soci
     SQLite::SQLite3
@@ -165,6 +163,13 @@ endif()
 ###
 
 include(RippledCore)
+if (NOT USE_CONAN)
+  include(deps/Protobuf)
+  include(deps/gRPC)
+else()
+  include(conan/Protobuf)
+  include(conan/gRPC)
+endif()
 include(RippledInstall)
 include(RippledCov)
 include(RippledMultiConfig)