feat: support icon and description in preset (#18977)

## Description 

This PR adds support for `description` and `icon` fields to
`template_version_presets`. These fields will allow displaying richer
information for presets in the UI, improving the user experience when
creating a workspace.
Both fields are optional, non-nullable, and default to empty strings.

## Changes

* Database migration with the addition of `description VARCHAR(128)` and
`icon VARCHAR(256)` columns to the `template_version_presets` table.
* Updated the `CreateWorkspacePageView` in the UI

Note: UI changes will be addressed in a separate PR

site/e2e/provisionerGenerated.ts

@@ -162,6 +162,8 @@ export interface Preset {
   parameters: PresetParameter[];
   prebuild: Prebuild | undefined;
   default: boolean;
+  description: string;
+  icon: string;
 }
 
 export interface PresetParameter {
@@ -715,6 +717,12 @@ export const Preset = {
     if (message.default === true) {
       writer.uint32(32).bool(message.default);
     }
+    if (message.description !== "") {
+      writer.uint32(42).string(message.description);
+    }
+    if (message.icon !== "") {
+      writer.uint32(50).string(message.icon);
+    }
     return writer;
   },
 };