fix: Add missing hitbox parameters

[mattmyne]

Description

This PR adds the position parameter to PolygonHitbox and isSolid parameters to all hitbox classes' .relative named constructors.

Also returns PolygonComponent's internal topLeft parameter to private _topLeft as no longer required outside of the class file.

Checklist

• The title of my PR starts with a Conventional Commit prefix (fix:, feat:, docs: etc).
• I have followed the Contributor Guide when preparing my PR.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• I have updated/added relevant examples in examples or docs.

Breaking Change?

• Yes, this PR is a breaking change.
• No, this PR is not a breaking change.

Related Issues

[mattmyne]

Adding the position parameter to PolygonHitbox also means the same vertices list used for (an optional) parent PolygonComponent can be reused in the PolygonHitbox constructor with position: Vector2.zero(). Previously position would be fixed at null and the hitbox would be offset by topLeft, with no way of correcting except to clone and modify the original vertices list.