Make it possible to link to other service/main site from Hajk

[jacobwod]

Overview

It turns out that there are cases where an organisation would want to link from the map view "back" to some other main landing site for the organisation. It might seem unnecessary given that user should be able to just open another tab and enter the URL (or have a bookmark in the browser…).

But one scenario where no such option is possible is when Hajk is running in kiosk mode on a touch device. This is a fairly common scenario in presentation lounges etc.

Documentation of the config options

Update 1
To enable this functionality, add the following to the map config JSON file:

// Make sure to remove the comments - they're not allowed in a plain JSON file
"linkInDrawer": {
    "href": "https://www.halmstad.se/", // URL to go to
    "newWindow": false, // Should the link open in a new tab or not? Adds `target="_blank"` if true.
    "text": "Gå till halmstad.se" // The text to display. Entire string will be clickable.
}

Update 2
Here's another example that clarifies the location of these new options in a map config file:

Requirements

1. Easy to reach on a touch device
2. Does not confuse user by overriding known functionality. This rules out making it a widget button or placing it in the toolbar, as those components already have a known functionality (namely opening a Hajk tool).
3. Should be visible (or can be configured to be visible) at startup
4. Non-obtrusive for current setups (if admin doesn't setup this URL, nothing should change in the UI)

Proposal

The best thing we can come up with is this:

[jacobwod]

We're in a hurry to get this into production so the first commit will not contain the Admin parts. Instead, this option will be configurable in the map config file.

[jacobwod]

The new link will always stay in the bottom. If there's no room, it will still be visible while the remains contents is scrollable.

[jacobwod]

I verified that (at least) the NodeJS backend does not override this setting when saving in Admin UI. This is the request body sent from Admin to Backend:

So we're safe (@FredrikEkstrom79) even without fixing this in Admin as of now. I can't say how .NET behaves though.

[Hallbergs]

Very nice addition!