[bug] Properly escape CMake generator expressions

[stevenwdv]

Describe the bug

Some CMake functions, like add_compile_definitions, accept generator expressions these take the form of $<...> and are only evaluated at generation time, not at configure time such as regular variables.
the CMakeToolchain conan uses some of these functions with dynamic values in conan_toolchain.cmake. This brings some problems, however, because values need to be escaped. For example:

add_compile_definitions("$<$<CONFIG:Debug>:{{define}}>")

with define=MYMACRO=abc $<CONFIG:Debug> def > 123 becomes:

add_compile_definitions("$<$<CONFIG:Debug>:abc $<CONFIG:Debug> def > 123>")

which will evaluate (in the debug config) as: abc 1 def >. Note that first assigning define to a CMake variable and using that in the expression as in "$<$<CONFIG:Debug>:${var}>" does not save us, as ${var} is evaluated at the configuration stage, before generation time.

To solve the issue, we need to escape (besides " and the usual):

• > as $<ANGLE-R>
• $ as $<1:$> (think: if(1) return "$")
• In some cases , and ; may need to be escaped as well.

Note that this should not just be done inside of generator expressions, but for all arguments that accept them, even if conan does not use them.

How to reproduce it

E.g. set tools.build:defines=['MYMACRO=abc $<CONFIG:Debug> def > 123'] and observe how the actual define passed to the compiler is not the same.