revert: "refactor: Clean up golden-layout css (#1322)"

[mofojed]

This reverts commit d1838d7.

Was getting build errors when consuming in Enterprise:

> Task :web-client-ui:ideClient FAILED
✓ 1043 modules transformed.
Could not resolve '../scss/GoldenLayout.module.css' from node_modules/@deephaven/golden-layout/dist/GoldenLayoutThemeExport.js
error during build:
Error: Could not resolve '../scss/GoldenLayout.module.css' from node_modules/@deephaven/golden-layout/dist/GoldenLayoutThemeExport.js
    at error (file:///Users/bender/dev/illumon/iris/web/client-ui/node_modules/rollup/dist/es/shared/rollup.js:1858:30)
    at ModuleLoader.handleResolveId (file:///Users/bender/dev/illumon/iris/web/client-ui/node_modules/rollup/dist/es/shared/rollup.js:22156:24)
    at file:///Users/bender/dev/illumon/iris/web/client-ui/node_modules/rollup/dist/es/shared/rollup.js:22119:26
ERROR: "build-js" exited with 1.

In the dist/GoldenLayoutThemeExport.js, the import ends up being:

import GoldenLayout from "../scss/GoldenLayout.module.css"; // parseInt for unitless values, stripping "px"

But in the scss folder it’s GoldenLayout.module.scss, not .css

The babel preset converts the scss imports to css:

    [
      'transform-rename-import',
      {
        // The babel-plugin-add-import-extension adds the .js to .scss imports, just convert them back to .css
        original: '^(.+?)\\.s?css.js$',
        replacement: '$1.css',
      },
    ],

Will need to resolve this issue before re-merging this refactor.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (main@4c3fe24). Click here to learn what that means.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##             main    #1334   +/-   ##
=======================================
  Coverage        ?   45.95%           
=======================================
  Files           ?      493           
  Lines           ?    34414           
  Branches        ?     8582           
=======================================
  Hits            ?    15814           
  Misses          ?    18549           
  Partials        ?       51           

Flag	Coverage Δ
unit	45.95% <0.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
packages/dashboard/src/PanelPlaceholder.tsx	40.00% <ø> (ø)
packages/dashboard/src/layout/LayoutUtils.ts	13.94% <0.00%> (ø)