[wgsl-in] Constructor improvements

[teoxoy]

Adds support for zero value constructors and constructors that infer their type from their parameters.

Also adds 4 more types of errors to better indicate issues with constructors.

For instance, before you could construct atomic types

var _ = atomic<i32>(0);

now you will get this error:

error: type `atomic` is not constructible
  ┌─ wgsl:3:25
  │
3 │                 var _ = atomic<i32>(0);
  │                         ^^^^^^ type is not constructible

closes #1733
closes #1774

References
Constructors
Zero value constructors

[kvark]

Very impressive work here!
We'll need a small pass to clean up some bits.

[kvark]

Glorious!