fix: remove eslint dependency from dev-scripts

[maribethb]

The basics

• I validated my changes

The details

Resolves

Fixes conflicts with dependencies because dev-scripts was bringing along an unused old copy of eslint

Proposed Changes

• Removes eslint dependency from dev-scripts. We already removed the script that actually ran eslint and we deleted the @blockly/eslint-config plugin a while ago, so this was installing the deprecated version from npm
• Removes the blockly-scripts lint script from the dev-create template (since that script hasn't existed for a while)
• Removes the same from the hacker theme

Note: to correctly lint any plugins in blockly-samples you just run npm run lint at the root. So individual plugins do not need the script. For third-party plugins, authors should set up their own linting without having to worry about the blockly team's style guide. This is not changing, this has already been the situation for a while

Reason for Changes

I've been having to force install some deps when using keyboard-navigation plugin because the plugin uses eslint 8 while devscript was "using" (depending on but not actually using) eslint 7

Test Coverage

¯\_(ツ)_/¯

Documentation

I don't think so

Additional Information