Support `add_dependencies` for targets

[mrexodia]

This is rather niche, but useful when dealing with CLion.

[target.exe]
type = "executable"
sources = [
    "src/exe/*.cpp",
    "src/exe/*.h",
    "src/exe/manifest.xml",
    "src/exe/resource.rc",
    "src/exe/strings.rc",
]
x86.sources = ["src/exe/icon32.rc"]
x64.sources = ["src/exe/icon64.rc"]
link-libraries = [
    "bridge",
    "Wintrust",
]
msvc.link-options = [
    "/DEF:${CMAKE_SOURCE_DIR}/src/exe/signaturecheck.def",
    "/INCREMENTAL:NO",
]
cmake-after = """
# Make the executable the main target
add_dependencies(exe dbg gui deps)
"""