Make debug log outputs neater

[ytoml]

While debug feature is helpful for debugging, there left some boring jobs like:

use erg_common::color::*;
log!("{GREEN}[DEBUG] msg {RESET}");

Currently, debug outputs look like:

Once we forget to end with "msg {RESET}", output are painted in all green and it is a little bit difficult to see. Also, handwritten [DEBUG] is not aligned due to different length of file/line info.

Thus, I introduced these fix in log! macro Changes proposed in this PR:

• Inserting [DEBUG] in front of file/line information to log in default.
• Forcing color reset for every log!
• Adding directives in log! to switch colors we like.
• Shorthand for green output(info) and red output(err)(for debugging, maybe warn is not necessary) (- documentation for log! directives above)

With these utilities, we can easily write neat logs with:

log!(info "compiler reached {}", fn_name!());
log!(err "error occured in {}!", fn_name!());

and outputs look like:

@mtshiba

[mtshiba]

Pretty good! Thank you!