viewer: migrate to vue 3, general refactoring and cleanup

Non-exhaustive list of fixes and improvements done at the same time:

- html default background to grey (avoids white flash during init)
- unified links behavior
- added more theme variables
- removed the flex-expand transition (it wasn't working) and replaced it
  with a slide
- fixed LdLoading not centered on the content
- title on removable tags
- fixed an issue with encoded URI from vue-router
- unified Item resource URLs
- removed the iframe for PlainTextViewer (it wasn't working properly)
  and replaced it with a pre
- fixed clear and search buttons tabindex
- fixed the information panel bumping up during the fade animation of
  tag's dropdown
- fixed some focus outlines not appearing correctly
- moved CSS variables to the :root context
- Code cleaning

GitHub: closes #217
GitHub: closes #300
GitHub: closes #297
GitHub: closes #105
GitHub: closes #267
GitHub: closes #275
GitHub: closes #228
GitHub: closes #215
GitHub: closes #112

1 files changed, 3 insertions, 2 deletions

diff --git a/viewer/babel.config.js b/viewer/babel.config.js
index ca2a3c1..757ff9b 100644
--- a/viewer/babel.config.js
+++ b/viewer/babel.config.js
@@ -1,4 +1,5 @@
 module.exports = {
-  presets: ["@vue/cli-plugin-babel/preset"],
-  plugins: [],
+  presets: [
+    '@vue/cli-plugin-babel/preset',
+  ],
 };