Refactor Wasmtime CLI to support components (#6836)

This commit refactors the `wasmtime` CLI executable to be able to
support not only compiling components but additionally executing
components. Whi

Refactor Wasmtime CLI to support components (#6836)

This commit refactors the `wasmtime` CLI executable to be able to
support not only compiling components but additionally executing
components. While I was doing this I've additionally added a new
`--preview2` argument to enable using the new experimental
implementation of preview1 based on preview2 type/structs. This is
off-by-default but is expected to become the default in the future.

Some notable features of this change are:

* The preview1-implemented-with-preview2 module now sports
`add_to_linker_{async,sync}` to replace the previous `add_to_linker`
which always did async.

* Some trait bounds in the preview1-implemented-with-preview2 module are
simplified.

* Some minor changes were made to `wiggle`'s macros to support a "block
on" that isn't the default wiggle dummy executor (as now we actually
do need Tokio)

* Many options related to core wasm `Linker` configuration, such as
`--default-values-unknown-imports`, are not implemented for components
at this time. When used with components these options return an error.

* Construction of WASI contexts has been refactored to pass around fewer
arguments to avoid threading through lots of values for both preview1
and preview2.

* Reading the input to the Wasmtime CLI has been updated to read the
input in the `run` subcommand before handing it off to the `wasmtime`
crate's API to enable the CLI to use the contents of what's loaded to
determine what to do next.

* Our generic `./ci/run-tests.sh` script has been updated to pass the
`--features component-model` flag to ensure that this CLI support is
tested during the normal test suite.

* The CLI support for `wasi-nn` supports components as well as core wasm
modules.

show more ...