Durable Object RPC stub (name interceptor)

[MellowYarker]

This is the client-side work that modifies DO client stubs, enabling them to intercept dynamic method names (those which are not defined on the C++ class).

The server-side PR will fill in the RPC branch of getNamed(), this commit just provides an interface and ensures "legacy" DO stub usage isn't broken.

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This is currently pointing to the jsg-named-intercept branch so the diff isn't annoying to look at. My plan is to rebase #1028 on this branch and delete most of the client side (actor.h/c++) stuff from that PR. Really, the only client side changes in that PR should be moving the body of getRpcAndCallRemote() into getNamed().

I'll be adding an internal test to confirm we can call stub.foo() if the compat flag is present, and perhaps more importantly, we can't without it (current stub behavior retained by default).

[MellowYarker]

Ah, almost forgot we want to prevent calling certain registered names (like alarm). Will add this just need to find the list of names.

[bcaimano]

The impl seems reasonable, most of my comments are around structuring this PR to land incrementally!

[kentonv]

This warning applies to adding methods to Fetcher too, right? Since it is inherited?

[jasnell]

Yeah, it will apply to any type that uses JSG_NAMED_INTERCEPT. But as mentioned in the other comment, we can tweak how this works by changing the flags we use to register the intercept callbacks. The current choice was made in an attempt to make it possible for existing jsg objects to continue to use the other macros easily (JSG_METHOD, JSG_*_PROPERTY, etc) while also supporting interception. But we have the freedom to change how the intercept works right now.

[bcaimano]

Looks like you'll need approval from @cloudflare/wrangler as well fyi

[MellowYarker]

Looks like you'll need approval from https://github.com/orgs/cloudflare/teams/wrangler as well fyi

Is there a way to replace this group? I wouldn't expect them to review this and I seem to be unable to remove the review request.

[mrbbot]

Looks like Wrangler's review request came from src/workerd/tools/api-encoder.c++, which is used in the automatic type generation. We're planning on replacing this soonish, so hopefully won't be a problem in the future. 👍

[MellowYarker]

https://github.com/cloudflare/workerd/compare/54b85d24528f9013d34a864f241c8e771fd8358d..244f9216b7c892d4227312e5cd42abb9956b3a0e is a rebase. I also dropped an include in actor.h that wasn't necessary.