build.ninja not generated with correct command line when path to (eg. clang) has a space in it (eg. "Program Files")

Describe the bug
The build.ninja file generated has the spaces in the path removed:

rule cpp_COMPILER
 command = "C:\Program" "Files\LLVM\bin\clang++.exe" $ARGS -MD -MQ $out -MF $DEPFILE -o $out "-c" $in
                       ^ if you change this to just a space instead of (" ") it works

This results in this error:

[1/2] Compiling C++ object ex.exe.p/main.cpp.obj
FAILED: ex.exe.p/main.cpp.obj
"C:\Program" "Files\LLVM\bin\clang++.exe" "-Iex.exe.p" "-I." "-I.." "-fcolor-diagnostics" "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-Wnon-virtual-dtor" 
"-g" -MD -MQ ex.exe.p/main.cpp.obj -MF "ex.exe.p\main.cpp.obj.d" -o ex.exe.p/main.cpp.obj "-c" ../main.cpp
CreateProcess failed: The system cannot find the file specified.
ninja: build stopped: subcommand failed.

The spaces are formatted incorrectly in the compile_commands.json as well.

To Reproduce
meson.build:

project('example', 'cpp', version: '1')
executable('ex', 'main.cpp')

main.cpp:

#include <iostream>
int main() { std::cout << "Hello world!" << std::endl; }

Expected behavior
It should compile.

system parameters

• Not a cross build
• Windows 10
• Python 3.9.4
• Meson 0.58.0
• Ninja 1.10.2

Reproduce the issue using the shown meson.build and main.cpp on Windows with a compiler path containing spaces. Inspect the generated build.ninja command and compile_commands.json quoting, then verify that both generated commands invoke clang++ successfully and the example compiles.