static fragment data passed to handlebars context

[scypio]

Static fragment data passed to the handlebars.

Description

During FragmentContext initialization static data (prefixed with data-const- is now passed stored into the context. Prefix used for these properties is _const. Therefore data attribute data-const-foo can be referenced from handlebars as {{_const.foo}]

Motivation and Context

Better code organization - and solution for some CMS systems that are not able to process the tags inside the fragment.

Implementation of https://github.com/Cognifide/knotx/issues/391

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.

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I hereby agree to the terms of the Knot.x Contributor License Agreement.

[scypio]

@Skejven changelog and upgrade notes updated :)

[tomaszmichalak]

This PR is outdated. Please check Knot.x 2.0 implementation to validate this idea.