Support per-project rdbgrc(.rb) files

[st0012]

Each project may have its own project-specific debugger configuration, like different paths to skip. So the debugger should also read rdbgrc files at the project root, similar to what irb does with irbrc.

[peterzhu2118]

Looks good!

Just a thought, maybe we could have a config option in ~/.rdbgrc that lets users turn off loading .rdbgrc in the project directory.

[st0012]

I think it can already be achieved with:

# ~/.rdbgrc.rb

# your configuration

ENV["RUBY_DEBUG_NO_RC"] = true

# ~/.rdbgrc

# your configuration

config set no_rc true