StorageBufferArrayDynamicIndexing capability missing

Given the following glsl compute shader
```glsl
#version 430
layout (local_size_x = 1, local_size_y = 1, local_size_z = 1) in;

layout (set = 0, binding = 0) buffer dat {
uint data[];
} ssboData[5];

void main() {
uint index = gl_GlobalInvocationID.x;
uint output_value = 0;
for (int i = 0; i < 4; ++i) {
output_value += ssboData[i].data[index];
}
ssboData[4].data[index] = output_value;
}
```

The StorageBufferArrayDynamicIndexing is not declared in the resulting SPIR-V module, meaning that indexing into ssboData must be with constant values.

Either StorageBufferArrayDynamicIndexing should be declared, or the module should fail compilation.
Alternatively the loop could be unrolled since every iteration is known at compile time.

It would also be nice to have a way to specify which features are available to be used in order to prevent accidentally emiting SPIR-V that cannot be consumed by a target environment. (I.e. similar to the limits).

Start by reproducing the provided GLSL compute shader and inspecting its generated SPIR-V module. Determine whether dynamic indexing should declare StorageBufferArrayDynamicIndexing or cause compilation to fail; the issue also raises loop unrolling and target-feature configuration as alternatives.

Written by the indexing model from the issue text.