Move core sonarkit code to xplat

Summary:
This diff only moves the core of sonarkit to the xplat.

- This diff uses `fb_xplat_cxx_library` as a buck rule in xplat as it is the recommended way
- Updated few imports in the files which were not compiling with new buck function
- Due to the new way of import the OSS would break, so fixed it by changing the `podspec` file

Reviewed By: passy

Differential Revision: D8937414

fbshipit-source-id: 6e12cd049bedb496e7a6820be85b2535e70ba09b

iOS/SonarKit.podspec

@@ -27,6 +27,14 @@ Pod::Spec.new do |spec|
     ss.public_header_files = 'iOS/FBDefines/**/*.h'
   end
 
+  spec.subspec 'CppBridge' do |ss|
+    ss.header_dir = 'CppBridge'
+    ss.compiler_flags = folly_compiler_flags
+    ss.source_files = 'iOS/SonarKit/CppBridge/**/*.{h,mm}'
+    ss.public_header_files = 'iOS/SonarKit/CppBridge/**/*.h'
+    ss.preserve_path = 'SonarKit/CppBridge/**/*.h'
+  end
+
   spec.subspec 'FBCxxUtils' do |ss|
     ss.header_dir = 'FBCxxUtils'
     ss.compiler_flags = folly_compiler_flags
@@ -39,6 +47,7 @@ Pod::Spec.new do |spec|
   spec.subspec "Core" do |ss|
     ss.dependency 'SonarKit/FBDefines'
     ss.dependency 'SonarKit/FBCxxUtils'
+    ss.dependency 'SonarKit/CppBridge'
     ss.dependency 'Folly', '~>1.0'
     ss.dependency 'Sonar', '~>'+sonarkit_version
     ss.dependency 'CocoaAsyncSocket', '~> 7.6'

iOS/SonarKit/CppBridge/SonarCppWrapperPlugin.h

@@ -10,7 +10,7 @@
 #endif
 
 #import <Sonar/SonarPlugin.h>
-#import <SonarKit/SonarCppBridgingConnection.h>
+#import <SonarKit/CppBridge/SonarCppBridgingConnection.h>
 #import <SonarKit/SonarPlugin.h>
 
 namespace facebook {

iOS/SonarKitTests/SonarCppBridgingTests.mm

@@ -9,7 +9,7 @@
 
 #if FB_SONARKIT_ENABLED
 
-#import <SonarKit/SonarCppWrapperPlugin.h>
+#import <SonarKit/CppBridge/SonarCppWrapperPlugin.h>
 #import <SonarKit/SonarPlugin.h>
 
 using facebook::sonar::SonarCppWrapperPlugin;