build: Use character literals for generated headers to avoid narrowing

Use character literals instead of integer hex values (i.e. `'\x5b','\x0a', ...` instead of `0x5b, 0x0a, ...`) for generated headers.
This avoids C++11 narrowing warnings in a more concise way than using explicit char casts.

Extra whitespace is also removed between elements for brevity.

cmake/script/GenerateHeaderFromJson.cmake

@@ -6,7 +6,7 @@ cmake_path(GET JSON_SOURCE_PATH STEM json_source_basename)
 
 file(READ ${JSON_SOURCE_PATH} hex_content HEX)
 string(REGEX REPLACE "................" "\\0\n" formatted_bytes "${hex_content}")
-string(REGEX REPLACE "[^\n][^\n]" "0x\\0, " formatted_bytes "${formatted_bytes}")
+string(REGEX REPLACE "[^\n][^\n]" "'\\\\x\\0'," formatted_bytes "${formatted_bytes}")
 
 set(header_content
 "#include <string_view>