Hotreloading of for/if/body, formatted strings, literals, component props, nested rsx

[jkelleyrtp]

Hotreload the contents of for loops, if chains, component bodies, props, and any literals discovered in rsx! or under the #[component] macro.

This is breaking since we need to open a bunch of APIs making this no longer compatible with all the support crates in 0.5. Anyways, plan is to ship by end of april so it's fine that we keep this PR out here for a while.

Specifics/todos:

• rewrite hotreload logic to allow collecting nested templates
• Hotreload logic for ifmt
• enable hotreload for textnodes
• enable hotreload for component props
• enable nested rsx! (focusing on props that are rsx)
• A more stable way of assigning IDs to literals/ifmts
• enable hotreload for generic literals (numbers, &str, etc)
• final passthru for cleanliness

Demo:

hotreload_strings.mov

props_reloaded_too.mov

[jkelleyrtp]

This is done, actually, but since it requires breaking changes to core, I'm gonna keep it open until we're ready to start merging break PRs.

I have since expanded the scope of this PR to include anything that seems feasibly hotreloadable.

This includes literals anywhere we can find them in components and global signals.

So you could in theory hotreload the majority of basic stuff:

#[component]
fn comp() {
    // Hot reload the value of x
    let x = 0;

    // Hot reload the value of 0
    if x == 0 {
        return rsx! {
            div { "Hello" }
        }
    }

    rsx! {
        // Or hot reload the iterator start and end
        for i in 0..10 {
            div { "World" }
        }
    }
}

My ultimate goal with all this work is to slap a little UI designer frontend on top that we can plug into devtools. This would let you do storybooks and UI construction without ever recompiling. Drag-and-drop UI builder, app route reloading, integration with gen AI etc.

Eventually eventually, get cranelift JIT up and running and then hotreload components themselves.

With the eventual cranelift work, we basically have Dart's hotreload engine and then can probably start to strip out the manual template-based hotreloading. I don't want to get too crazy with hotreloading now since that work will probably make most of this work moot, but the timelines there are much longer.

[DogeDark]

Will this include hot reloading for workspaces? Would massively speed up components in combo with a manganis issue fixed.