feat: filter which event (UP/DOWN/CERT-EXPIRY) triggers alerts

[DVDAndroid]

📋 Overview

This PR introduces the ability to customize which types of events trigger notifications.

🔄 Changes

Migration on notification table: column trigger of type text and default value up,down,certificate.

Changed edit monitor page and edit notification dialog.

🛠️ Type of change

• 🐛 Bugfix (a non-breaking change that resolves an issue)
• ✨ New feature (a non-breaking change that adds new functionality)
• ⚠️ Breaking change (a fix or feature that alters existing functionality in a way that could cause issues)
• 🎨 User Interface (UI) updates
• 📄 New Documentation (addition of new documentation)
• 📄 Documentation Update (modification of existing documentation)
• 📄 Documentation Update Required (the change requires updates to related documentation)
• 🔧 Other (please specify):
  • Provide additional details here.

🔗 Related Issues

• Resolves Filter which event (UP/DOWN/CERT-EXPIRY/...) triggers alerts #508

📄 Checklist *

• 🔍 My code adheres to the style guidelines of this project.
• ✅ I ran ESLint and other code linters for modified files.
• 🛠️ I have reviewed and tested my code.
• 📝 I have commented my code, especially in hard-to-understand areas (e.g., using JSDoc for methods).
• ⚠️ My changes generate no new warnings.
• 🤖 My code needed automated testing. I have added them (this is an optional task).
• 📄 Documentation updates are included (if applicable).
• 🔒 I have considered potential security impacts and mitigated risks.
• 🧰 Dependency updates are listed and explained.
• 📚 I have read and understood the Pull Request guidelines.

📷 Screenshots or Visual Changes

ℹ️ Additional Context

💬 Requested Feedback

[CommanderStorm]

I don't like how this looks in the UI (this does not reaaaly fit the rest of the UI).
Here are some pointers:

• Expired certificates are avaliable here https://expired.badssl.com/
• Please use a multiselector instead. I think that is much more user friendly than the current dropdown
• please have a look at how we space/align the rest of the UI, that is currently quite messy
• More foundamental: Not sure where in the notification window this should be placed and how.
  Currently looks quite out of place. I think by default, this should be more out of the way
  => Maybe a link text at the bottom "customise which alerts trigger this notification provider"
• I think the ability to customise for each monitor (instead of just at the notification provider level) what alerts trigger the notification provider is likely overkill and looks quite messy => lets just display an information tag icon which on hover shows that this does only trigger for XYZ