Issue title: ToolTip does not work on SVG
 Issue body: **Describe the bug**
ToolTip does not work on SVG

**To Reproduce**
Steps to reproduce the behavior:

1. Put something like the following line:

`<Svg Path="..." ToolTip.Tip="foobar" />`

or

`<Image Source="{SvgImage ...}" ToolTip.Tip="foobar" />`

2. Move pointer over image
3. ToolTip doe not open


**Expected behavior**
The ToolTip will be open as on other controls too.

**Desktop (please complete the following information):**

- OS: Windows
- Version: 10

**Additional context**

Dan Walmsley recommended me this as a workaound:
```
                            <Panel>
                                <Svg ... />
                                <Panel Background="Transparent"
                                       ToolTip.Tip="...." />
                            </Panel>
```

 Comments: 
 Comment 0: We don't maintain the SVG control so I don't this is the right place for your issue
 Comment 1: https://github.com/wieslawsoltes/Svg.Skia is a correct place for this issue.
{'source': 'GithubIssues', 'repo_name_with_owner': 'AvaloniaUI/Avalonia', 'issue_id': 1180825287, 'repo_stars': 15769.0}