spike: Experiment with chaining links together

[claremacrae]

This is an experiment to aid discussion on:

• Getting TasksFile out of Link object? #3627

It's purely so that a build is created, for users to experiment with this implementation and give feedback.

There is no intention to merge this branch to main.

Feedback

Please put any feedback in:

• Getting TasksFile out of Link object? #3627

How to test this

1. Go to https://github.com/obsidian-tasks-group/obsidian-tasks/actions/runs/18124750481
2. Download and expand the file dist-verified file
3. You will now have a new Tasks distribution which you can add in to your main vault, or a test vault

The Changes

This adds:

• task.file.propertyAsLink('property-name') - which returns the property as a Link or a null
• Link.asFile() which returns a TasksFile representing the link destination, or null

For context, TasksFile is the type of task.file.

An example of use, based on 4 test files that I added in PR...

```tasks
filename includes chain_link

# TODO Make 'group by' detect if the object is a link, and group by its markdown

group by function 'Level 1 link: ' + \
    task.file.\
        propertyAsLink('link_to_file').markdown

group by function 'Level 2 link: ' + \
    task.file.\
        propertyAsLink('link_to_file').asFile().\
        propertyAsLink('link_to_file').markdown

group by function 'Level 3 link: ' + \
    task.file.\
        propertyAsLink('link_to_file').asFile().\
        propertyAsLink('link_to_file').asFile().\
        propertyAsLink('link_to_file').markdown

group by function 'Level 4 link: ' + \
    task.file.\
        propertyAsLink('link_to_file').asFile().\
        propertyAsLink('link_to_file').asFile().\
        propertyAsLink('link_to_file').asFile().\
        propertyAsLink('link_to_file').markdown

```

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud