refactor: create useDirty composable

[Sekhmet]

Currently we handle dirty flag, but it's not ideal (when loading already populated form it won't trigger because value has to be modified manually, we could solve this via use of composable and apply it across the app:

import { ModelRef } from 'vue';

type Definition<T> = {
  default?: T;
};

export function useDirty<T>(model: ModelRef<T>, definition: Definition<T>) {
  const modelModified = ref(false);

  const dirty = computed(() => {
    if (modelModified.value) return true;
    if (definition.default && model.value !== definition.default) return true;
    return !!model.value;
  });

  watch(model, () => {
    modelModified.value = true;
  });

  return {
    dirty,
    modelModified
  };
}