Inconsistencies with --cfg=erase_components

[sabify]

Describe the bug
By using --cfg=erase_components in RUSTFLAGS, leptos ignores attr: in components and nothing will be applied.

Leptos Dependencies
leptos = "0.7.0-rc0"

Steps to reproduce the behavior:

1. use RUSTFLAGS="--cfg=erase_components" cargo leptos serve
2. Add an attribute to a component: <ActionForm attr:class="xyz">
3. On serve, no class attribute is added

Expected behavior
The class attribute should be added to the component.

[gbj]

This is unfortunate but known. After much work I was not able to support adding arbitrary attributes to AnyView without causing difficult-to-reproduce linker crashes on larger projects. You can read the length discussion beginning here.

You can add #[component(transparent)] to components that need to support attribute spreading and that should work.

[zakstucke]

@gbj maybe for now we should enable the dodgy impl when --cfg=erase_components is turned off? At the moment I suppose this would affect release builds when into_any() is legitimately used.

[gbj]

@zakstucke To the best of my knowledge, there has never been a non-todo!() implementation of AddAnyAttr for AnyView that did not lead to linker errors. If anyone has a fix for that, I will be very excited!