feat(darkmode): dark mode toggle (#82)

* feat(darkmode): initial support for dark mode toggle

* fix(darkmode): add svg icons

* feat(darkmode): dispatch onColorSchemeChange event

* add head/darkmode

* feat(darkmode); add colorScheme config

* style: remove empty line

* refactor(darkmode): simplify code

* style: add comment for darkmode config

* i18n support for dark mode toggle

* Some renaming

assets/scss/partials/menu.scss

@@ -129,6 +129,8 @@
     margin-top: var(--sidebar-element-separation);
     margin-bottom: 0;
     overflow-y: auto;
+    flex-grow: 1;
+    font-size: 1.5rem;
 
     @media (min-width: $on-desktop-large) {
         margin-top: 30px;
@@ -192,7 +194,6 @@
             display: inline-flex;
             align-items: center;
             color: var(--body-text-color);
-            font-size: 1.5rem;
 
             @media (max-width: $on-desktop-large) {
                 font-size: 1.4rem;