Cleaning up the P/Invoke signatures for QPF and QPC to avoid marshalling and...

Cleaning up the P/Invoke signatures for QPF and QPC to avoid marshalling and pinning (dotnet/coreclr#36071)

* Cleaning up the P/Invoke signatures for QPF and QPC to avoid marshalling and pinning

* Responding to PR feedback.

* Dropping support for low resolution stopwatch

* Removing BestFitMapping=false

* Removing unneeded unsafe declarations

* Addressing more PR feedback

* Fixing the pal_time header file

* Fixing the Unix P/Invoke signatures for GetTimestamp and GetTimestampResolution to return ulong.

* Fixing GetTimestampResolution to scale the result for HAVE_CLOCK_MONOTONIC
Signed-off-by: Ndotnet-bot <dotnet-bot@microsoft.com>


Commit migrated from https://github.com/dotnet/coreclr/commit/aa072b639fc2eb0e60a8083e4c74426db91341e0

src/libraries/System.Private.CoreLib/src/Interop/Unix/System.Native/Interop.GetTimestamp.cs

@@ -8,10 +8,10 @@ internal static partial class Interop
 {
     internal static partial class Sys
     {
-        [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_GetTimestampResolution")]
-        internal static extern bool GetTimestampResolution(out long resolution);
+        [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_GetTimestampResolution", ExactSpelling = true)]
+        internal static extern ulong GetTimestampResolution();
 
-        [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_GetTimestamp")]
-        internal static extern bool GetTimestamp(out long timestamp);
+        [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_GetTimestamp", ExactSpelling = true)]
+        internal static extern ulong GetTimestamp();
     }
 }