[vcpkg-tool] Add a cmake preset for boostrap-vcpkg.sh

[SchaichAlonso]

scripts/bootrap.sh does some rather interesting composition of a cmake call around lines 214 which results in having to use eval to get rid of the double-escaping of some strings.

Further, the ninja-specific multi-task build job rules are quite nasty and probably don't provide us with anything that passing --parallel to cmake --build could also do.

Add a CMakePreset.json representing the cmake invokation of bootstrap.sh, and replace the ninja specific code by --build - or - if the ninja specialization has to stay, derive a ninja multi-tasking preset from the regular, which allows simplifying the bootstrap script, as well as invoking cmake in a vcpkg-tool checkout.