Search widget RAW_QUERY parameter

### Description

Current search widget configuration:
```
- type: search
search-engine: duckduckgo
new-tab: true
bangs:
- title: Github Repository
shortcut: "!ghr"
url: https://github.com/{RAW_QUERY}
```

I need the ability to use the raw query parameter without the URL encoding

Currently:
`!ghr glanceapp/glance` -> `https://github.com/glanceapp%2Fglance`

With raw query param
`!ghr glanceapp/glance` -> `https://github.com/glanceapp/glance`

Start at the search widget's bang URL expansion, using the shown {RAW_QUERY} configuration and the encoded URL as the reproduction. Done means the raw-query form preserves the slash in glanceapp/glance while ordinary query handling remains unchanged; verify the behavior with the search widget's relevant checks.

Written by the indexing model from the issue text.