Split it so that it can be reused in the EE repository:

 - static-build/cmake/AddDependencyProjects.cmake
   Adds the external projects that are required to build tarantool.
   The project names are stored in the TARANTOOL_DEPENDS variable.

 - static-build/cmake/AddTarantoolProject.cmake
   Should be called after AddDependencyProjects.cmake, because it
   uses the TARANTOOL_DEPENDS variable. Adds the Tarantool external
   project and sets the TARANTOOL_BINARY to the path to the built
   tarantool binary.

 - static-build/cmake/AddTests.cmake
   Should be called after AddTarantoolProject.cmake, because it uses
   the TARANTOOL_BINARY variable. Adds cmake tests for the static
   binary.

Now, static-build/CMakeLists.txt just includes the three helper files.
The helper files are designed in such a way that they can be included
from the EE repository's CMakeLists.txt. We split the original config
into the three helper files, because in the EE repository, we need to
add extra dependency projects and extra tests.

While we are at it, we also move the cmake tests from
static-build/test/static-build to static-build/test and
static-build/test/CheckDependencies.cmake to
static-build/cmake/CheckDependencies.cmake.

This commit introduces no functional changes - it just moves the code.

Needed for https://github.com/tarantool/tarantool-ee/issues/185

NO_DOC=refactoring
NO_TEST=refactoring
NO_CHANGELOG=refactoring