WIP: Initial support for setting a server identifier

[nneul]

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Description

Fixes #3827

Implement a "Server Identifier" that will be appended to "Uptime Kuma" when shown in the UI, Title, Notifications. This will allow more easily distinguishing notifications, active tabs, etc.

I am NOT a Vue/Node developer, so if there is something just "eeew" in this, please let me know and I'll try to adjust accordingly. Suggestions are highly appreciated.

The title of the page updates only on page load, wasn't sure where/how to get that to update on the fly.

Type of change

• User interface (UI)
• New feature (non-breaking change which adds functionality)

Checklist

• My code follows the style guidelines of this project
• I ran ESLint and other linters for modified files
• I have performed a self-review of my own code and tested it
• I have commented my code, particularly in hard-to-understand areas (including JSDoc for methods)
• My changes generates no new warnings
• My code needed automated testing. I have added them (this is optional task)

Screenshots (if any)

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