@solid-primitives/resize-observer: Implement new strategies for determining element size and revert changes in 2.0.22

[vveisard]

Describe The Problem To Be Solved

The new strategy for createElementSize introduced in 2.0.22 (which to be fair, is more reasonable) is not backwards compatible. Instead, additional strategies for calculating element size should be added which respect semantic versioning.

In my case, I was using createElementSize for proportional scaling to change the transform: scale style of the observed element. Using bounding client rect breaks this behavior.

Suggest A Solution

I have two suggestions, both of which are minor revisions (2.1.0) that respect semantic versioning:

1. Deprecate createElementSize and create new primitives for each strategy:

• createElementBorderBoxSize
• createElementContentBoxSize
• createElementContentRectSize
• createElementBoundingClientRectSize

2. Like the suggestion in Use contentBoxSize and borderBoxSize instead of contentRect in createElementSize #469, add a strategy parameter to createElementSize for how to calculate the size; 'borderBoxSize' | 'contentBoxSize' | 'contentRect' | 'getBoundingClientRect'. The default value of this parameter is contentRect, which match the behavior prior to 2.0.22.