Polyfill `ToWasmtimeResult` and add eventually-necessary call sites (#12308)

* Polyfill `ToWasmtimeResult` and add eventually-necessary call sites

This commit polyfills `wasmtime_internal_error::To

Polyfill `ToWasmtimeResult` and add eventually-necessary call sites (#12308)

* Polyfill `ToWasmtimeResult` and add eventually-necessary call sites

This commit polyfills `wasmtime_internal_error::ToWasmtimeResult` in
`wasmtime_environ`, adds the cargo feature plumbing that will eventually connect
to the `"wasmtime_internal_error/anyhow"` cargo feature but for now just
configures this polyfill, and adds uses of the polyfill at all the sites that
will be necessary once we swap out `anyhow` for
`wasmtime_internal_error`. Currently, the polyfill is just an identity function,
because `wasmtime::Result`/`wasmtime_environ::error::Result` is just another
name for `anyhow::Result`. Once we do move away from `anyhow`, however, that
will no longer be the case, and these uses will do the necessary conversion.

My goal with landing this as an incremental commit is to make it so that the
actual commit that does the error crate swap out can be as close to _just_ the
`Cargo.toml` dependency change, without any other code changes as much as
possible. This, in turn, means that swap out should be super easy to revert, if
necessary.

* Add a couple more `.to_wasmtime_result()` invocations in fuzz code

* Revert "Add a couple more `.to_wasmtime_result()` invocations in fuzz code"

This reverts commit b33696e5f63f7eed731ca9dad10fec5e55a550d3.

* Move cranelift fuzz targets back to anyhow

* Fix cargo feature enablement for explorer

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Migrate explorer to `wasmtime::error` (#12262)

More clearly flag internal crates as such (#10963)

* More clearly flag internal crates as such

This commit is an attempt to more clearly flag internal crates in this
project as internal and not int

More clearly flag internal crates as such (#10963)

* More clearly flag internal crates as such

This commit is an attempt to more clearly flag internal crates in this
project as internal and not intended for external use. Specifically:

* Many crates are renamed from `wasmtime-foo` to
`wasmtime-internal-foo`.
* All of these crates now have `INTERNAL: ...` in their crates.io
description.
* All of these crates now have a warning at the top of their
documentation discouraging use.

This change is a result of rustsec/advisory-db#1999 where the goal is to
be crystal clear from a project perspective that usage of these crates
are highly discouraged and not supported. We'll still probably get such
advisories but we won't be considering them CVEs from the project itself
due to the internal nature of these crates and the discouraging
warnings.

Some concrete changes used here are:

* Inter-crate dependencies still use `wasmtime_foo` for naming and do
so with Cargo's package-renaming features.
* Crate renames are specified at the workspace level so the rename is
only in one locations and all other inherit it.
* Contribution documentation now has some brief guidelines about crate
organization.

* Update vet config

* Update checks for wasmtime-fiber

prtest:full

* Update publish script

* Another fiber rename

* Fix some doc tests

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