core: Can't assign "props" to "state"

we need a way to assign `props` to `state`
https://github.com/BuilderIO/mitosis/blob/main/docs/gotchas.md#cant-assign-params-to-state

we can either inject the workaround into onMount or for some generators

Start with docs/gotchas.md at “Can’t assign params to state” to understand the current limitation and workaround. Then inspect the compiler’s generator handling and the onMount path to determine whether the behavior belongs in generated output or a shared transformation. Done means props can be assigned to state without requiring the documented workaround, with the affected generators covered.

Written by the indexing model from the issue text.