Implement text-in-shape and text-on-path.

I wanted to hack this together, because one of the things that bothered me with T16862 is that there are a few oddities with the KoShape system that make it really hard to discuss if you are not aware of them:

1. The dependee system is necessary even with simple embedded shapes, as it allows for those to send updates to the main text shape.
2. The "scale styles" option works inverse from what you expect: when it is enabled, it sets a transform, when disabled, it tries to use "setSize" on the KoShape in question.

Beyond that, I'm just really really worried about scope.

TODO

• Contour mode:
  • The base implementation point is KisCanvas2::shapeManager()
  • when contour editing mode is activated, KisCanvas2::localShapeManager() will create a special KoShapeManager object for the contents of the text shape (might be returned via KoShape::internalShapes()). There will be problems with update signals, the change should be done very carefully.
  • This local shape manager will have its own KoSelection that will handle selections. Normal shapes of the layer will not be available.
  • This internal shape manager should use dummy canvas (just inherit the resolution from the actual layer’s canvas (might be not needed))
• Saving - Invisible shapes will be added to defs, visible shapes to special group shape.
• Rendering
• setSize Unittest
• Rotation unittest?
• Functioning UI.
  • Contour mode button.
  • Flow in Shape command
  • Subtract from flow command
  • Remove shape from flow command
  • toggle shape in flow command
  • reorder shapes in flow area.
  • set textpath on range
  • undo set textpath from range
  • edit text path info
  • strategy for text path info
  • shape padding/margin sliders.
  • Speedups for shape padding/margin?
  • strategy for shape padding/margin
  • Fix slowdown setSize()

Above: Current look and feel in text tool. There's a text inside a series of wrapping areas, with said wrapping areas computer from shape-inside/shape-subtract, shape padding and shape margins. The arrows between the wrapping areas show the order in which the areas are used for layout.

Testing:

I've implemented the ability to create a text in shape (with an embedded shape) (layout was already possible).

1. Create a few path shapes on a vector layer. (save this if you want to test this branch a bunch of times)
2. Now, with the text tool selected, hover over a shape -> the icon will change to a T inside a rectangle with two rounded corners.
3. Click the shape -> You now have a text in shape. You can type and use the text properties docker to set the size and whatnot.

Creating a text path is done by hovering over the border of the shape, until the icon changes to a text-on-path icon. Then click.

And I've create a "setSize" for the text shape:

4. Select the "Select Shapes/Default Tool", try to scale the text in shape. In some cases, this is still bugged.
5. Create and scale a non-text-in-shape. This (right now) applies a basic scale.

Save and load should work fine.

Editing shapes when they're part of a text shape can be done by clicking the new top right icon to enter "contour mode".

Shape-Padding and Shape Margin have been added in the text properties docker under paragraph->Text Area. You can also change these by dragging the text area bounds inside the text tool. Warning: these are slow

Shape Selection Tool

The rightclick menu of the shape selection tool has received a number of new actions under "text":

• "Flow text in shapes" and "Subtract shapes from text flow" adds the shape as a inside or subtract shape respectively and are only enabled when text and non-text shapes are selected.
• The others are only available in Contour mode, and will adjust the order of the shapes inside or toggle a given shape between subtract and inside, or just remove the shape.
• When in contour mode, default tool will treat the parent text as the target for the text properties adjustments.

see also woltherav/krita#33 (closed) and T16862 BUG:391796

Formalities Checklist

• I confirmed this builds.
• I confirmed Krita ran and the relevant functions work.
• I tested the relevant unit tests and can confirm they are not broken. (If not possible, don't hesitate to ask for help!)
• I made sure my commits build individually and have good descriptions as per KDE guidelines.
• I made sure my code conforms to the standards set in the HACKING file.
• I can confirm the code is licensed and attributed appropriately, and that unattributed code is mine, as per KDE Licensing Policy.
• Does the patch add a user-visible feature? If yes, is there a documentation MR ready for it at Krita Documentation Repository?