Preserve classes on internal links using the scLink directive

[callmeaponte]

This change prevents classes from being wiped on anchor elements using the scLink directive.

Description

For Angular JSS projects, classes are preserved on anchor elements that use external Sitecore links:

<a class="foo bar" *scLink="externalLinkData"></a> <!-- before -->
<a class="foo bar" href="" alt=""></a> <!-- after -->

... However when using internal Sitecore links, the classes are wiped:

<a class="foo bar" *scLink="internalLinkData"></a> <!-- before -->
<a href="" alt=""></a> <!-- before -->

Motivation

#378

How Has This Been Tested?

First, I ran npm run test-packages. Next, I packaged a local version of the npm package (.tgz file) and added it to our project. Then I confirmed that the CSS class wipe issue was fixed.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update (non-breaking change; modified files are limited to the /docs directory)

Checklist:

• I have read the Contributing guide.
• My code follows the code style of this project.
• My code/comments/docs fully adhere to the Code of Conduct.
• My change is a code change and it requires an update to the documentation.
• My change is a documentation change and it requires an update to the navigation.