[wgsl-in] Immutable array cannot be accessed with mutable index

[HactarCE]

Description
An array assigned to an immutable variable cannot be accessed using an index from a mutable binding.

Repro steps
Compile this code in a WGSL shader:

fn f() {
    let a = array<f32, 10>();

    let i = 0;
    let x = a[i]; // compiles fine

    var j = 0;
    let y = a[j]; // error: The expression may only be indexed by a constant
}

Expected vs observed behavior
I expect f to compile with no issue, but instead I get an error when attempting to access a[j].

Platform

• OS: macOS Sonoma 14.2
• wgpu: latest from trunk

[nical]

Duplicate of #4337