Add escalation notifications for persistent incidents

[jaidentwyman]

Describe your changes

Added escalation notifications for monitors. Users can now configure escalation channels and a delay in the UI. On incident creation, a delayed job is scheduled; if the incident is still active after the delay, escalation notifications are sent with higher urgency messaging

Write your issue number after "Fixes "

Fixes #1

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

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

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