all: Format code to add space after C++-style comment start.

Note: the uncrustify configuration is explicitly set to 'add' instead of
'force' in order not to alter the comments which use extra spaces after //
as a means of indenting text for clarity.

tools/uncrustify.cfg

@@ -853,7 +853,7 @@ sp_extern_paren                 = ignore   # ignore/add/remove/force
 
 # Add or remove space after the opening of a C++ comment,
 # i.e. '// A' vs. '//A'.
-sp_cmt_cpp_start                = ignore   # ignore/add/remove/force
+sp_cmt_cpp_start                = add      # ignore/add/remove/force
 
 # If true, space is added with sp_cmt_cpp_start will be added after doxygen
 # sequences like '///', '///<', '//!' and '//!<'.