Support validation of multiple entry points invocations in rst files

[kbenzie]

The discussion in #591 (comment) shows that it is not possible to split a entry-point invocation in a code block of a reStructuredText document over multiple lines, otherwise it fails validation and blocks generation of the rendered HTML.

Generating ../docs/source/core/CONTRIB.rst...
Generating ../docs/source/core/EXP-COMMAND-BUFER.rst...
/home/ben/dev/intel/unified-runtime/scripts/core/EXP-COMMAND-BUFER.rst(114) : error : $xCommandBufferAppendMemcpyUSMExp parameter count mismatch - 6 actual vs. 7 expected
line =     ${x}CommandBufferAppendMemcpyUSMExp(hCommandBuffer, pDst, pSrc, size, 0,

Failed to generate specification.
FAILED: CMakeFiles/generate-code /home/ben/dev/intel/unified-runtime/build/CMakeFiles/generate-code 
cd /home/ben/dev/intel/unified-runtime/scripts && /usr/bin/python3.8 run.py --api-json /home/ben/dev/intel/unified-runtime/build/unified_runtime.json && /usr/bin/python3.8 json2src.py --api-json /home/ben/dev/intel/unified-runtime/build/unified_runtime.json /home/ben/dev/intel/unified-runtime
ninja: build stopped: subcommand failed.
FAILED: CMakeFiles/generate /home/ben/dev/intel/unified-runtime/build/CMakeFiles/generate 
cd /home/ben/dev/intel/unified-runtime/build && /usr/local/bin/cmake --build /home/ben/dev/intel/unified-runtime/build --target generate-code && /usr/local/bin/cmake --build /home/ben/dev/intel/unified-runtime/build --target cppformat
ninja: build stopped: subcommand failed.

This should be supported because it enforces entry points in example code to be defined in a single line. This is problematic for entry points with a large number of arguemnts, or long argument names, because it requires scrolling sideways and reducing the clarify of documentation.