DEV: Reduce width calculations for SK dropdowns (#18263)

Previously we were calculating both the minimum and maximum widths for
SK dropdowns using this Popper modifier. The max. width calculation was
causing issues with dropdowns in Firefox and was also sluggish when
rendering.

This switches to using CSS calculations for max. widths. It adds a 600px
global maximum and targeted maximums for the category composer dropdown
and the bookmark list dropdowns.

app/assets/javascripts/select-kit/addon/components/select-kit.js

@@ -940,7 +940,7 @@ export default Component.extend(
               },
             },
             {
-              name: "sameWidth",
+              name: "minWidth",
               enabled: window.innerWidth > 450,
               phase: "beforeWrite",
               requires: ["computeStyles"],
@@ -949,24 +949,12 @@ export default Component.extend(
                   state.rects.reference.width,
                   220
                 )}px`;
-
-                if (state.rects.reference.width >= 300) {
-                  state.styles.popper.maxWidth = `${state.rects.reference.width}px`;
-                } else {
-                  state.styles.popper.maxWidth = "300px";
-                }
               },
               effect: ({ state }) => {
                 state.elements.popper.style.minWidth = `${Math.max(
                   state.elements.reference.offsetWidth,
                   220
                 )}px`;
-
-                if (state.elements.reference.offsetWidth >= 300) {
-                  state.elements.popper.style.maxWidth = `${state.elements.reference.offsetWidth}px`;
-                } else {
-                  state.elements.popper.style.maxWidth = "300px";
-                }
               },
             },
             {

app/assets/stylesheets/common/base/compose.scss

@@ -245,6 +245,10 @@ html.composer-open {
         text-overflow: ellipsis;
       }
 
+      .select-kit-body {
+        max-width: 450px;
+      }
+
       // below needed for text-overflow: ellipsis;
       .selected-name {
         max-width: 100%;

app/assets/stylesheets/common/base/edit-category.scss

@@ -134,10 +134,6 @@ div.edit-category {
         .filter-input {
           min-width: 250px;
         }
-
-        .select-kit-body {
-          max-width: 100%;
-        }
       }
     }
 

app/assets/stylesheets/common/components/bookmark-list.scss

@@ -73,3 +73,9 @@ $mobile-breakpoint: 700px;
     }
   }
 }
+
+.select-kit.bookmark-actions-dropdown {
+  .select-kit-body {
+    max-width: 350px;
+  }
+}

app/assets/stylesheets/common/select-kit/select-kit.scss

@@ -42,6 +42,7 @@
       border: 1px solid var(--primary-low);
       box-shadow: shadow("dropdown");
       background: var(--secondary);
+      max-width: 600px;
     }
 
     .select-kit-collection {