Add helpers to all selectors (#12230)

src/components/ha-selector/ha-selector-addon.ts

@@ -14,6 +14,8 @@ export class HaAddonSelector extends LitElement {
 
   @property() public label?: string;
 
+  @property() public helper?: string;
+
   @property({ type: Boolean }) public disabled = false;
 
   @property({ type: Boolean }) public required = true;
@@ -23,6 +25,7 @@ export class HaAddonSelector extends LitElement {
       .hass=${this.hass}
       .value=${this.value}
       .label=${this.label}
+      .helper=${this.helper}
       .disabled=${this.disabled}
       .required=${this.required}
       allow-custom-entity