Relace node-sass with dart-sass

This patchset moves phosphor-webui away from node-sass.  This is a good
thing overall, and should make phosphor-webui build a little faster,
given it doesn't have to compile libsass.  It also dumps a significant
number of dependencies from the tree.

webui-vue has a similar patch:
https://gerrit.openbmc-project.xyz/c/openbmc/webui-vue/+/35663

Tested:
Build phosphor-webui with changes.  Builds as expected.

Change-Id: I30537284518ebf2e0816568e25320a55ade323e4
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/package.json b/package.json
index fd51898..f44d0fd 100644
--- a/package.json
+++ b/package.json
@@ -76,11 +76,10 @@
     "html-webpack-plugin": "4.2.0",
     "ignore-assets-webpack-plugin": "2.0.1",
     "mini-css-extract-plugin": "0.9.0",
-    "node-gyp": "6.1.0",
-    "node-sass": "4.13.1",
     "null-loader": "4.0.0",
     "raw-loader": "4.0.1",
     "rimraf": "3.0.2",
+    "sass": "1.26.10",
     "sass-loader": "8.0.2",
     "style-loader": "1.1.4",
     "svg-inline-loader": "0.8.2",