Move DS caching from user level to the HAL (#1143)

Also switch eventName and gameSpecificData to fixed 64-byte arrays to avoid mallocs and
extra NetComm calls.  This behavior matches 2018 LabView.

The DS caching is kept in Java to avoid JNI and/or massive amounts of allocations.
This does not increase latency because Java still only hits NetComm once.

Moving the DS caching benefits all languages other than Java, because it avoids the need
for individual implementations.  If caching is ever added to NetComm, it will then only be
necessary to remove it from the HAL and Java rather than all languages.

hal/src/main/native/cpp/jni/HAL.cpp

@@ -407,7 +407,6 @@ Java_edu_wpi_first_wpilibj_hal_HAL_getMatchInfo
   if (status == 0) {
     SetMatchInfoObject(env, info, matchInfo);
   }
-  HAL_FreeMatchInfo(&matchInfo);
   return status;
 }