[Repo Assist] Fix custom attribute encoding for generative type providers

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Two related fixes to custom attribute encoding in the generative type provider assembly compiler (AssemblyCompiler / defineCustomAttrs).

Fix 1: Implement array support in encodeCustomAttrElemTypeForObject

Before: Passing an obj[] (or typed array like string[]) as an argument to an Object-typed custom attribute constructor parameter would throw:

failwith "TODO: can't yet emit arrays in attrs"
```

**After:** Infers the element type from the runtime array type and encodes `SZARRAY + element type byte` per ECMA-335 §II.23.3. Supported element types: `string`, `bool`, `char`, `sbyte`/`byte`, `int16`/`uint16`, `int32`/`uint32`, `int64`/`uint64`, `single`, `double`, and `obj` (encoded as `OBJECT`).

## Fix 2: Apply `transValue` to all custom attribute argument values

**Before:** `transValue` (which translates `System.Type` → `ILType`) was defined inside `defineCustomAttrs` but never used — the function was dead code. Constructor arguments and named properties/fields were passed through untranslated.

**After:** `transValue` is moved before its first use and applied to:
- All constructor fixed arguments (`constructorArgs`)
- Named property values (`namedProps`)
- Named field values (`namedFields`)

This ensures that if a custom attribute argument contains a `System.Type` value (e.g., `typeof(SomeProvidedType)`), it is translated to the target `ILType` and the correct type name is encoded in the binary attribute blob.

## Root cause

Both issues affect **generative type providers** only. Erased providers reflect attributes directly without going through ECMA-335 binary encoding.

## Test Status

All existing tests pass: **104 passed, 0 failed** on net8.0.

```
Passed!  - Failed: 0, Passed: 104, Skipped: 0, Total: 104

Note: the new functionality (array args, Type args in attrs) is exercised by the fixes themselves but no dedicated integration test is added — adding one would require a new generative provider test fixture with attributes using these specific parameter patterns.

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