escalation notifications

[ckulhanjian]

Describe your changes

I implemented escalation notifications as a configuration option when monitoring a site. Updated frontend to display the options and stored values in backend and database.

Write your issue number after "Fixes "

Fixes #123

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• (Do not skip this or your PR will be closed) I deployed the application locally.
• (Do not skip this or your PR will be closed) I have performed a self-review and testing of my code.
• I have included the issue # in the PR.
• I have added i18n support to visible strings (instead of <div>Add</div>, use):

const { t } = useTranslation();
<div>{t('add')}</div>

• I have not included any files that are not related to my pull request, including package-lock and package-json if dependencies have not changed
• I didn't use any hardcoded values (otherwise it will not scale, and will make it difficult to maintain consistency across the application).
• I made sure font sizes, color choices etc are all referenced from the theme. I don't have any hardcoded dimensions.
• My PR is granular and targeted to one specific feature.
• I ran npm run format in server and client directories, which automatically formats your code.
• I took a screenshot or a video and attached to this PR if there is a UI change.