Pull changes from solid-metrics repository

[n-bernat]

Pulled code from the solid-metrics repository with the following changes:

• [x] Renamed everything from “Solid Metrics” (and its variants) to “Solid Lints”
• [x] Removed unused dependencies on flutter and custom_lint from pubspec.yaml
• [x] Removed analysis_options.yaml from test directory due to a bug in custom_lint
• [x] Updated .gitignore to ignore custom_lint’s log file

To be added:

• [x] ~Bump the version from 0.1.0 to 0.1.1~ We will have a dedicated 0.1.0 release with the whole migration

[solid-yuriiprykhodko]

Bump the version from 0.1.0 to 0.1.1

We can skip this and ship the whole custom_lints migration under 0.1.0. Just add the relevant stuff to the CHANGELOG

[solid-yuriiprykhodko]

We probably want a set of lint rules to validate the Dart code. solid_lints is the default option for us, don't think there should be any issues plugging them in?

[n-bernat]

@solid-yuriiprykhodko rules from solid_lints apply to the code in lib as we are in this project and analysis_options.yaml is propagated to all subdirectories automatically