Fixes: https://github.com/woodpecker-ci/woodpecker/issues/1079
What do you think about using a consistent `woodpecker` color scheme?
Right now, the `lime` color scheme from windicss is used that does not
really fit the primary color used for the documentation website. I have
used the primary color `#4CAF50` from the docs and created a color
palette with https://palettte.app/:
<details>
<summary>JSON source</summary>
```Json
[
{
"paletteName": "New Palette",
"swatches": [
{
"name": "New Swatch",
"color": "166E30"
},
{
"name": "New Swatch",
"color": "248438"
},
{
"name": "New Swatch",
"color": "369943"
},
{
"name": "New Swatch",
"color": "4CAF50"
},
{
"name": "New Swatch",
"color": "68C464"
},
{
"name": "New Swatch",
"color": "8AD97F"
}
]
}
]
```
</details>

I have added this color scheme to the windicss config and replaced the
use of `lime` in the UI. While `woodpecker-300` would be the primary
color that is used for the docs, I currently use `woodpecke-400` as
primary color for the UI to fix some contrast issues.


What do you think? If you would like to stay with the current colors,
that's fine for me, I can just use the custom CSS feature in this case.
---------
Co-authored-by: 6543 <6543@obermui.de>
Save which agent is running a task. This is now visible in the admin UI
in the queue and in the agent details screen.
# changes
- [x] save id of agent executing a task
- [x] add endpoint to get tasks of an agent for #999
- [x] show assigned agent-id in queue
- [x] (offtopic) use same colors for queue stats and icons (similar to
the ones used by pipelines)
- [x] (offtopic) use badges for queue labels & dependencies

# Changes
- Adds an admin view to see the whole work-queue of the server.
- The admin can also pause / resume the queue.
- The view is reloading data every 5 seconds automatically.
- The task model from queue got removed in favor of the one from models.