fix remaining non-a11y eslint issues

[bcullman]

see commented out rules in https://github.com/SAP/fundamental-react/blob/master/.eslintrc

they are:

#brace-style: 2
#compat/compat: 2
#eqeqeq: 2
#indent: [2, 4, {"SwitchCase": 1}]
#no-console: 2
#no-empty: 2
#no-nested-ternary: 2
#no-shadow: 2
#no-sparse-arrays: 2
#no-undefined: 2
#no-unused-vars: [2, { ignoreRestSiblings: true }]
#radix: 2
#react/jsx-sort-props: 2
#react/no-multi-comp: 2
#react/prop-types: 2
#react/react-in-jsx-scope: 2
#sort-imports: [2, { 'ignoreCase': true, 'ignoreMemberSort': false, 'memberSyntaxSortOrder': ['none', 'single', 'multiple', 'all'] }]
#use-isnan: 2
#valid-jsdoc: [2, { prefer: { 'return': 'returns'}}]
#valid-typeof: 2

[bcullman]

for tracking purposes, it would be best to handle fixing each lint rule as its own PR - ie, a single PR should NOT be used to fix all of these simultaneously.

[greg-a-smith]

I have created a Wiki page to track our progress on each rule so people are not working on the same items. Please update the Wiki page when you work on a rule.

https://github.com/SAP/fundamental-react/wiki/ESLint-Rules

[greg-a-smith]

The only rule that wasn't fixed was react/no-multi-comp and that's up for debate amongst the team as to the best route forward. If it were to be implemented, it would be a large-scale refactoring effort and a separate story.