Move ThreadManagerType enum to ThriftServer

Summary:
# Project goal
As part of Better Engineering effort, merge `BaseThriftServer` class into `ThriftServer` class to simplify and unify server development process.

# Iterative change
Move `ThreadManagerType` enum to `ThriftServer`, as part 2 of `ThreadManager` move.

Rename `BaseThriftServer::ThreadManagerType` to `ThriftServer::ThreadManagerType` in all files in fbcode.

Reviewed By: fadimounir

Differential Revision: D55542271

fbshipit-source-id: 09e560fa9f07c07998db1e3bc3cb34cea752c858

openr/Main.cpp

@@ -252,7 +252,7 @@ main(int argc, char** argv) {
   if (config->isNetlinkFibHandlerEnabled()) {
     netlinkFibServer = std::make_unique<apache::thrift::ThriftServer>();
     netlinkFibServer->setThreadManagerType(
-        apache::thrift::BaseThriftServer::ThreadManagerType::PRIORITY_QUEUE);
+        apache::thrift::ThriftServer::ThreadManagerType::PRIORITY_QUEUE);
     netlinkFibServer->setNumCPUWorkerThreads(2 /* num of threads */);
     netlinkFibServer->setCPUWorkerThreadName("ThriftCpuPool");