FIX: Relax excessive ESLint configuration rules

[dsriseah]

Ben reports that it's difficult to work with all the extra errors reported in the component files as he does MUI conversion.

This PR partially addresses #21, updating the ESLint configuration to relax rules that the new prettier/prettier ruleset (which is now a superset prettier/react) introduced. ESLint now has more recommendations than in 2018, and I have relaxed some of them to "warn" level, while others are off. For a complete list, check the .estlintrc.js file.

NOTE: I left in several rules that do reveal issues that should be addressed and are pretty easy to do.

ESLINTRC TEST

• instead of pulling the branch, go to dev-sri/build-config-fixes/.eslintrc.js to grab the .eslintrc.js file
• in your current working repo, paste the .eslintrc.js file next to where your .eslintrc.json file is
• rename .eslintrc.json to old-eslintrc.json
• quit visual studio code, then reopen
• report if the eslintrc flagging looks any better than before
• look at the output for ESLintrc and see if there are errors.

NOTE: ESLint only checks on open files, so you'll have to click around to see.

OTHER CHANGES

This PR also includes updates to .vscode folder default snippets and settings, affecting FormatOnSave settings using a more "global" approach and removing the LiveShare extension as a recommended extension

[benloh]

Thanks for the fixes! This'll go a long way towards focusing on the key lint fixes.