cmake: support build using Ninja

By default CMake generates Makefiles for building a project. However, it
allows to generate Ninja files. Ninja [1] may build project a bit faster
than Make, see [2].

Patch adds fixes for CMake files allowing to use Ninja for building
Tarantool:

1. Fixed dependencies in ExternalProject_Add(), see explanation in [3]
2. Fixed ninja error due to presence of symbol '$' in cmake/rpm.cmake
3. Added propagation of CMAKE_GENERATOR in dependencies that uses CMake
   for building, see [4]

How-to build wit Ninja:

$ cmake -G Ninja -B build -S .
$ ninja -C build/

1. https://ninja-build.org/
2. https://mesonbuild.com/Simple-comparison.html
3. https://stackoverflow.com/a/65803911/3665613
4. https://cmake.org/cmake/help/latest/module/ExternalProject.html

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