Ordering of keys with objectKeys

**Bicep version**

Bicep CLI version 0.27.1 (4b41cb6d4b)

**Describe the bug**

The `objectKeys` function is described by:

> Returns an array of object keys. Elements are consistently ordered alphabetically.

While this is technically true, it also might be ambiguous in the context of character casing.

**To Reproduce**

Consider:

```bicep
output example3 string[] = objectKeys({ a: 1, b: 2 }) // returns [ 'a', 'b' ]
output example3a string[] = objectKeys({}) // returns []
output example3b string[] = objectKeys({ b: 2, a: 1 }) // returns [ 'a', 'b' ]
output example3c string[] = objectKeys({ A: 2, a: 1 }) // returns [ 'A', 'a' ]
output example3d string[] = objectKeys({ a: 2, A: 1 }) // returns [ 'a', 'A' ]
```

In short `A` and `a` from the example are not sorted.

While unlikely to occur on standard ARM resource properties in isolation. Flagging that this might cause non-deterministic behaviour that is confusing for customers.

Start with the objectKeys documentation and the supplied Bicep examples, then locate the implementation or tests covering object-key ordering. Done when the behavior for keys that differ only by case is deterministic and the documented wording and regression coverage reflect the agreed behavior.

Written by the indexing model from the issue text.