enhance: tiny improvements to Settings (#3279)

This PR looks more substantial than it really is. The key changes in UX are:

Add buttons for Edit custom.css and Customize config.edn to the Settings modal.
Consolidate the Customize Shortcuts settings tab with the General tab.
(Reasoning: Since the former only had one item, it didn't warrant a whole separate tab.)

Beyond that, all of the other changes are small refactors (e.g. extracting repetitive code into reusable functions, fixing inconsistent whitespace) or tiny tweaks to copy (i.e. making text more concise / easier to read on the page).

src/main/frontend/components/settings.css

@@ -111,7 +111,8 @@
         }
 
         .form-select, .form-input {
-          width: 55%;
+          width: 100%;
+          max-width: 200px;
           display: inline-block;
 
           &:hover {
@@ -207,7 +208,6 @@
 
     .ctls {
       position: relative;
-      top: -8px;
 
       &:disabled {
         cursor: progress;
@@ -215,10 +215,11 @@
     }
 
     .update-state {
-      padding: 15px;
+      padding: 6px 10px;
       background-color: var(--ls-quaternary-background-color);
       border-radius: 4px;
-      margin-bottom: -8px;
+      margin-top: 10px;
+      width: fit-content;
 
       > p {
         margin: 0;
@@ -244,6 +245,10 @@
   }
 }
 
+/* Styles for the category icon on the left of settings-modal */
+.cp__settings-inner > aside ul > li > a > i {
+  margin-right: 4px;
+}
 
 svg.git {
     margin-left: -4px;