fix(site): pass all properties of a multi-select dynamic parameter option to MultiSelectCombobox defaultOptions (#27145)

fixes DEVEX-463

Previously, a dynamic parameter of `form_type = "multi-select"` with
default options selected would only pass in these 3 properties for each
option fed into `MultiSelectCombobox`'s `defaultOptions`:

- `value`
- `label`
- `disable` 

`defaultOptions` are used as the initial value of
`MultiSelectCombobox`'s `selected` array of `Option`s. If the `icon`
property is missing from a selected option, then no icon is shown:


https://github.com/coder/coder/blob/e59a67d63fd522d1e95b42e57d4fbfe7d2bc5fef/site/src/components/MultiSelectCombobox/MultiSelectCombobox.tsx#L501-L502

Now `icon` and `description` are included among those properties passed
to default selected options, when a default option's value can be found
among the parameter's available options in the Terraform template. This
fixes the bug where icons wouldn't display for default selected options.

If no corresponding option is found, then we fall back to the old
partial option object (`{ value, label, disable }`).

<img width="1840" height="1191" alt="Screenshot 2026-07-09 at 10 08
54 PM"
src="https://github.com/user-attachments/assets/91be4aaf-9016-46d6-871b-344c8f2504cb"
/>

site/src/modules/workspaces/DynamicParameter/DynamicParameter.tsx

@@ -373,18 +373,15 @@ const ParameterField: FC<ParameterFieldProps> = ({
 				disable: false,
 			}));
 
-			const optionMap = new Map(
-				parameter.options.map((opt) => [opt.value.value, opt.name]),
+			const selectedOptions: Option[] = parsedValues.values.map(
+				(val) =>
+					options.find((o) => o.value === val) ?? {
+						value: val,
+						label: val,
+						disable: false,
+					},
 			);
 
-			const selectedOptions: Option[] = parsedValues.values.map((val) => {
-				return {
-					value: val,
-					label: optionMap.get(val) || val,
-					disable: false,
-				};
-			});
-
 			return (
 				<MultiSelectCombobox
 					inputProps={{