Configure Xdebug modes

[iandunn]

It'd be nice to have Xdebug's develop mode on by default, for readable var_dump()s.

The other modes might be useful as alternate start scripts, like:

"env": "wp-env start --xdebug=develop",
"env:debug": "wp-env start --xdebug=debug,develop",
"env:profile": "wp-env start --xdebug=profile",

That didn't work for me at first glance, but I haven't dug into it.

xref https://github.com/WordPress/gutenberg/tree/trunk/packages/env#using-xdebug