ArrowBytesMap and ArrowBytesViewMap undercount memory by not accounting for initial hash table allocation

### Describe the bug

`ArrowBytesMap` and `ArrowBytesViewMap` allocate their hash tables with `HashTable::with_capacity(INITIAL_MAP_CAPACITY)` (128 and 512 entries respectively) but initialize `map_size` to `0`. The `size()` method returns `map_size` as the hash table's contribution to total memory.

The `insert_accounted` method (from `HashTableAllocExt`) only adds to `map_size` when the table needs to grow beyond its current capacity. Since the initial allocation happens in `with_capacity`, not through `insert_accounted`, those bytes are never counted — `size()` understates memory usage until the first resize.

```rust
// binary_map.rs — INITIAL_MAP_CAPACITY = 128
// binary_view_map.rs — INITIAL_MAP_CAPACITY = 512
pub fn new(output_type: OutputType) -> Self {
Self {
map: hashbrown::hash_table::HashTable::with_capacity(INITIAL_MAP_CAPACITY),
map_size: 0, // ← should be map.allocation_size()
// ...
}
}
```

`insert_accounted` only tracks growth:
```rust
fn insert_accounted(&mut self, x: Self::T, hasher: impl Fn(&Self::T) -> u64, accounting: &mut usize) {
if self.len() == self.capacity() {
let bump_size = self.capacity().max(16) * size_of::();
*accounting = (*accounting).checked_add(bump_size).expect("overflow");
self.reserve(bump_elements, &hasher);
}
self.insert_unique(hash, x, hasher);
}
```

### To Reproduce

N/A

### Expected behavior

`map_size` should be initialized with `map.allocation_size()` to account for the pre-allocated memory from `with_capacity`.

### Additional context

Two other uses of `map_size: 0` in the codebase (`row.rs` and `multi_group_by/mod.rs`) use `HashTable::with_capacity(0)` which allocates nothing, so they are already correct.

Start by reading binary_map.rs and binary_view_map.rs, focusing on each map's with_capacity initialization and size accounting. Compare the zero-capacity HashTable uses in row.rs and multi_group_by/mod.rs, then verify that the reported sizes include the initial allocations for both map types.

Written by the indexing model from the issue text.