feat(types): adjust type exports for manual render function and tooling usage

- v-model and v-show directives are now exposed as public
- compiler-used runtime helpers are now exposed for TS tooling, but marked as @private

close #1329

packages/runtime-core/src/helpers/renderSlot.ts

@@ -12,7 +12,7 @@ import { warn } from '../warning'
 
 /**
  * Compiler runtime helper for rendering <slot/>
- * @internal
+ * @private
  */
 export function renderSlot(
   slots: Slots,