Remove duplicated command_config.py file

[taraxacum45e9a]

The file (linker/slashkit/command_config.py) is exactly the same as (linker/slashkit/core/command_config.py), and only the one under core is actually used.

This PR removes the file linker/slashkit/command_config.py which is duplicated and unused.

Details

$ shasum linker/slashkit/command_config.py linker/slashkit/core/command_config.py
1d6e15d36a6fd964e973d6ecb0b6538ff34796bd  linker/slashkit/command_config.py
1d6e15d36a6fd964e973d6ecb0b6538ff34796bd  linker/slashkit/core/command_config.py

$ rg command_config       
linker/slashkit/__main__.py
40:from slashkit.core.command_config import LinkerConfiguration, Platform, InstallerConfiguration, CommandConfiguration

linker/slashkit/emit/emu/project_gen.py
35:from slashkit.core.command_config import LinkerConfiguration

linker/slashkit/emit/emu/tcl_gen.py
31:from slashkit.core.command_config import LinkerConfiguration

linker/slashkit/emit/hw/project_gen.py
35:from slashkit.core.command_config import LinkerConfiguration, InstallerConfiguration, CommandConfiguration

linker/slashkit/emit/hw/tcl_gen.py
44:from slashkit.core.command_config import LinkerConfiguration

linker/slashkit/emit/sim/project_gen.py
30:from slashkit.core.command_config import LinkerConfiguration

linker/slashkit/emit/sim/tcl_gen.py
33:from slashkit.core.command_config import LinkerConfiguration

linker/slashkit/emit/metadata/prog_image.py
26:from slashkit.core.command_config import LinkerConfiguration