Size verifier fix 2 (#8740)

* Fixes to make SizeVerifier work.

In particular change all the places in the Flatbuffers library
and generated code that were using `Verifier` to instead use
`VerifierTemplate<TrackBufferSize>` and wrap them all inside
`template <bool TrackBufferSize = false>`.

Also add unit tests for SizeVerifier.

* Format using `sh scripts/clang-format-git.sh`

* Use `B` rather than `TrackBufferSize` for the name of the template parameter.

* Update generated files.

include/flatbuffers/flex_flat_util.h

@@ -23,9 +23,10 @@
 namespace flexbuffers {
 
 // Verifies the `nested` flexbuffer within a flatbuffer vector is valid.
+template <bool B>
 inline bool VerifyNestedFlexBuffer(
     const flatbuffers::Vector<uint8_t>* const nested,
-    flatbuffers::Verifier& verifier) {
+    flatbuffers::VerifierTemplate<B>& verifier) {
   if (!nested) return true;
   return verifier.Check(flexbuffers::VerifyBuffer(
       nested->data(), nested->size(), verifier.GetFlexReuseTracker()));