Fix SCSS code style order of properties

[richard67]

Pull Request for Issue #105 (part).

Summary of Changes

Fixes all SCSS code style errors found by the stylelint tool in the Cassiopeia template's SCSS files, except of one Unexpected duplicate "position" error found here:

https://github.com/joomla/cassiopeia/blob/development/templates/cassiopeia/scss/blocks/_back-to-top.scss#L22-L23

Is seems this one can't be avoided.

Testing Instructions

Checkout the branch of this PR, then run composer install and npm ci, then run
node ./node_modules/stylelint/bin/stylelint.js --config build/.stylelintrc.json -s scss "templates/**/*.scss"
in the Joomla root folder.

Actual result BEFORE applying this Pull Request

templates/cassiopeia/scss/blocks/_back-to-top.scss
 23:3  >  Unexpected duplicate "position"                  declaration-block-no-duplicate-properties
 25:3  >  Expected "top" to come before "pointer-events"   order/properties-order                   

templates/cassiopeia/scss/blocks/_global.scss
 108:3  >  Expected "padding" to come before "margin-bottom"   order/properties-order

templates/cassiopeia/scss/blocks/_layout.scss
 55:3  >  Expected "flex" to come before "flex-direction"   order/properties-order

templates/cassiopeia/scss/tools/mixins/_visually-hidden.scss
 25:3  >  Expected "overflow" to come before "clip"     order/properties-order
 26:3  >  Expected "height" to come before "overflow"   order/properties-order
 27:3  >  Expected "width" to come before "height"      order/properties-order
 40:5  >  Expected "overflow" to come before "clip"     order/properties-order
 41:5  >  Expected "height" to come before "overflow"   order/properties-order
 42:5  >  Expected "width" to come before "height"      order/properties-order

Expected result AFTER applying this Pull Request

templates/cassiopeia/scss/blocks/_back-to-top.scss
 23:3  > Unexpected duplicate "position"   declaration-block-no-duplicate-properties

Documentation Changes Required

None.