[chore] Refactor `StreamProcessor` into separate classes

Dismembers StreamProcessor into the following hierarchy, with the equivalent functionality in square brackets:

1. Processor [PASS_THROUGH]
   1. BrilProcessor [BRIL]
   2. OrbitProcessor
      1. GmtOrbitProcessor [GMT]
      2. CaloOrbitProcessor [CALO]

This change will support subsequent extensions to the processing step, with specific functionality for different GMT primitives, etc.

This MR avoids making style changes to the original code to prevent clutter and make the review process easier. Therefore, clang formatting and the Google C++ Style guide are sometimes ignored. A follow-up MR will apply the style changes.

src/MicronDmaInputFilter.cc

@@ -89,7 +89,7 @@ ssize_t MicronDmaInputFilter::runMicronDAQ(char **buffer) {
   uint32_t packetSize;
   int err;
 
-  if (processorType_ == StreamProcessor::ProcessorType::BRIL) {
+  if (processorType_ == Config::ProcessorType::BRIL) {
     packetSize = 32 * 1791;  // fixed bril 1-histo packet size
   } else {
     packetSize = 32 * (*((uint32_t *)((*buffer) + 8)) + 2);