:four_leaf_clover: `Proposal`: support apply config directory

[steinliber]

What Would You Like to Add? Why Is This Needed?

We support getting config from a file for now. but for more complex config maybe using a directory to save configs is a better choice.

Design

• if the user run the command dtm apply -f {{dir_name}}, dtm should read all config files in this directory and generate config for the following process

[steinliber]

The current core config is We can add config varFiles and toolFiles to support multi-tool config and var config, like below or can use the directory directly

[daniel-hutao]

If it's because the current config file is already too long, I agree with splitting.