Added the code to embed the binary schema to the source (--bfbs-gen-embed). (#5701)

* Added the code to embed the binary schema to the source.
This is pulled forward from a old PR #5162 that will be closed.

* Update idl_gen_cpp.cpp

Added a small comment to trigger a new build. The build was failing in a strange location and doesn't look like it has anything to do with the code.

* Moved the EscapeAndWrapBuffer to util.cpp and did some formating.

* One more camelCases removed and renamed some variables.

* wrapped_line_xxx should have been passed as a const reference in the first place.

* Moved the bfbs embed sample to it's own file.

* Missed moving the namespace back.

* Moved the embedded bfbs to test.cpp instead of using a sample.

* Missed adding the generation of embedded bfbs to the build.

* See if this makes the build happier.

* Fixed a in-compatable cpp output of the generated header.

* Did some changes to reflect the code review comments.
1. Update the EscapeAndWrapBuffer to BufferToHexText and fixed a variable name.
2. Moved the include of the embedded binary schema to all the other includes.

* Moved some code to inline the instead of using a local variable.

* Moved the BufferToHexText back to be a inline function in util.h

src/util.cpp

@@ -274,4 +274,5 @@ void SetupDefaultCRTReportMode() {
   // clang-format on
 }
 
+
 }  // namespace flatbuffers