Fix stlyelint deprecation warnings

[vzDevelopment]

I get the following deprecation warnings when I run webpack:

WARNING in ./~/css-loader!./~/postcss-loader!./~/stylelint-loader!./client/css/app.css
config:deprecated 'at-rule-empty-line-before's' "blockless-group" option has been deprecated and in 8.0 will be removed. Instead use the "blockless-after-blockless" option.

WARNING in ./~/css-loader!./~/postcss-loader!./~/stylelint-loader!./client/css/app.css
config:deprecated 'declaration-block-no-ignored-properties' has been deprecated and in 8.0 will be removed.

WARNING in ./~/css-loader!./~/postcss-loader!./~/stylelint-loader!./client/css/app.css
config:deprecated 'media-feature-no-missing-punctuation' has been deprecated and in 8.0 will be removed.

WARNING in ./~/css-loader!./~/postcss-loader!./~/stylelint-loader!./client/css/app.css
config:deprecated 'rule-non-nested-empty-line-before' has been deprecated and in 8.0 will be removed. Instead use 'rule-empty-line-before'.

[vzDevelopment]

https://stylelint.io/CHANGELOG/ provides information as to why these are deprecated:

"blockless-group" option for at-rule-empty-line-before. Use the "blockless-after-blockless" option instead.

The following rules did not work well...declaration-block-no-ignored-properties could not reliably account for replaced elements.

It is beyond the scope of stylelint's core package to effectively validate against the CSS spec. Please investigate csstree and css-values for this functionality, and contribute to those projects and to stylelint plugins wrapping them. csstree already has a stylelint plugin, and css-values needs one to be developed. The following rules are deprecated for this reason.
media-feature-no-missing-punctuation

Deprecated: 15 rules
rule-nested-empty-line-before and rule-non-nested-empty-line-before. Use the new rule-empty-line-before rule instead.

Doing some Googling for these I can see other people have followed the guidelines where it says to use another option instead and for the others they have just deleted them. I've done the same with our stylelint.config.js.

After rebuilding with webpack the deprecation warnings are gone and the UI functionality is working as it was before.