This addresses bytecodealliance#4310, introducing a new `component::values::Val` type for
representing component values dynamically, as well as `component::types::Type`
for representing the corresponding interface types. It also adds a `call` method
to `component::func::Func`, which takes a slice of `Val`s as parameters and
returns a `Result<Val>` representing the result.

Note that I've moved `post_return` and `call_raw` from `TypedFunc` to `Func`
since there was nothing specific to `TypedFunc` about them, and I wanted to
reuse them.  The code in both is unchanged beyond the trivial tweaks to make
them fit in their new home.

Signed-off-by: Joel Dice <joel.dice@fermyon.com>

Signed-off-by: Joel Dice <joel.dice@fermyon.com>

This also removes the redundant `store` parameter from `Type::load`.

Signed-off-by: Joel Dice <joel.dice@fermyon.com>

This fixes a few issues:

- Bad offset calculation when lowering
- Missing variant padding
- Style issues regarding `types::Handle`
- Missed opportunities to reuse `Lift` and `Lower` impls

It also adds forwarding `Lift` impls for `Box<[T]>`, `Vec<T>`, etc.

Signed-off-by: Joel Dice <joel.dice@fermyon.com>

Per review feedback, I've moved `Type::new_record` to `Record::new_val` and
added a `Type::unwrap_record` method; likewise for the other kinds of types.

Signed-off-by: Joel Dice <joel.dice@fermyon.com>

These types should compare as equal across component boundaries as long as their
type parameters are equal.

Signed-off-by: Joel Dice <joel.dice@fermyon.com>

We now distinguish between more failure cases to provide an informative error
message.

Signed-off-by: Joel Dice <joel.dice@fermyon.com>

- Remove `WasmStr::to_str_from_memory` and `WasmList::get_from_memory`
- add `try_new` methods to various `values` types
- avoid using `ExactSizeIterator::len` where we can't trust it
- fix over-constrained bounds on forwarded `ComponentType` impls

Signed-off-by: Joel Dice <joel.dice@fermyon.com>

- Move functions from `types` to `values` module so we can make certain struct fields private
- Rename `try_new` to just `new`

Signed-off-by: Joel Dice <joel.dice@fermyon.com>

Instead, I've added a FIXME comment and will open an issue to do recursive
structural equality testing.

Signed-off-by: Joel Dice <joel.dice@fermyon.com>