[cm6] Highlight the active visible line (#10441)

* Remove background opacity from selection
* Remove highlightActiveLine and highlightActiveLineGutter extensions
* Add new highlightActiveLine extension
* Adjust zIndex for layers
* Ensure the output file ends with a newline
* Update themes
* Remove the active line highlight when text is selected
* Disable emptyLineFiller temporarily

GitOrigin-RevId: a3228d3441ee2eac136768c3d0788ec471559cd9

services/web/package.json

@@ -272,8 +272,6 @@
     "chai-as-promised": "^7.1.1",
     "chai-exclude": "^2.0.3",
     "cheerio": "^1.0.0-rc.3",
-    "color-alpha": "^1.1.3",
-    "color-parse": "^1.4.2",
     "content-disposition": "^0.5.0",
     "copy-webpack-plugin": "^10.2.4",
     "css-loader": "^6.7.1",