refactor(app): migrate env var form section [EE-6232] (#10499)

* refactor(app): migrate env var form section [EE-6232]

* allow undoing delete in inputlist

app/react/components/form-components/EnvironmentVariablesFieldset/EnvironmentVariableItem.tsx

@@ -0,0 +1,59 @@
+import { FormError } from '../FormError';
+import { InputLabeled } from '../Input/InputLabeled';
+import { ItemProps } from '../InputList';
+
+import { EnvVar } from './types';
+
+export function EnvironmentVariableItem({
+  item,
+  onChange,
+  disabled,
+  error,
+  readOnly,
+  index,
+}: ItemProps<EnvVar>) {
+  return (
+    <div className="relative flex w-full flex-col">
+      <div className="flex w-full items-start gap-2">
+        <div className="w-1/2">
+          <InputLabeled
+            className="w-full"
+            label="name"
+            required
+            value={item.name}
+            onChange={(e) => handleChange({ name: e.target.value })}
+            disabled={disabled}
+            needsDeletion={item.needsDeletion}
+            readOnly={readOnly}
+            placeholder="e.g. FOO"
+            size="small"
+            id={`env-name${index}`}
+          />
+          {error && (
+            <div>
+              <FormError className="mt-1 !mb-0">
+                {Object.values(error)[0]}
+              </FormError>
+            </div>
+          )}
+        </div>
+        <InputLabeled
+          className="w-1/2"
+          label="value"
+          value={item.value}
+          onChange={(e) => handleChange({ value: e.target.value })}
+          disabled={disabled}
+          needsDeletion={item.needsDeletion}
+          readOnly={readOnly}
+          placeholder="e.g. bar"
+          size="small"
+          id={`env-value${index}`}
+        />
+      </div>
+    </div>
+  );
+
+  function handleChange(partial: Partial<EnvVar>) {
+    onChange({ ...item, ...partial });
+  }
+}