Enable all lints by default

[Conrad33]

The README of custom_lint states:

By default, custom_lint enables all installed lints.

But this isn't the case for solid_lints. (See #163) There is an open issue for the dart linter that has some context as to why this behavior is desirable. I believe solid_lints should enable all the lints by default.

It's worth noting that including a file in analysis_options.yaml like:

include: package:solid_lints/analysis_options.yaml

Isn't currently a great solution because only one file can be included, so this can't be used with a package like all_lint_rules_community.