Add -fdefer-diagnostics to defer and group diagnostic messages in make-mode

When loading many modules in parallel there can a lot of warnings and
errors get mixed up with regular output. When the compilation fails,
the relevant error message can be thousands of lines backward and is
hard to find. When the compilation successes, warning message is likely
to be ignored as it is not seen. We can address this by deferring the
warning and error message after the compilation. We also put errors
after warnings so it is more visible.

This idea was originally proposed by Bartosz Nitka in
https://phabricator.haskell.org/D4219.

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