VPN Gateway Connection module ignores route map IDs in routing configuration

### Check for previous/existing GitHub issues

- [x] I have checked for previous/existing GitHub issues

### Issue Type?

Bug

### (Optional) Module Version

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### (Optional) Correlation Id

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### Description

## Bug Report

### Module Version
- **Version:** v0.14.0
- **Module Path:** `modules/site-to-site-gateway-conn`

### Description
The VPN Gateway Connection submodule defines `inbound_route_map_id` and `outbound_route_map_id` in its variables but doesn't use them in the resource configuration, causing route maps to be ignored.

### Expected Behavior
When `inbound_route_map_id` or `outbound_route_map_id` are provided in the routing configuration, they should be applied to the `azurerm_vpn_gateway_connection` resource.

### Current Behavior
Route map IDs are accepted as input variables but ignored in the resource creation, causing Terraform to show drift and attempt to remove manually configured route maps.

### Root Cause
**File:** [modules/site-to-site-gateway-conn/main.tf](cci:7://file:///Users/dilpreetsingh/workspace/stash/azure/azure-core/production/vWAN/prod-eastus/.terraform/modules/vwan_prod_east_us/modules/site-to-site-gateway-conn/main.tf:0:0-0:0)
**Lines:** 52-67

The `routing` dynamic block only handles:
- `associated_route_table` ✅
- `propagated_route_table` ✅
- `inbound_route_map_id` ❌ (missing)
- `outbound_route_map_id` ❌ (missing)

### Code Fix Required

**Current code (lines 55-56):**
```hcl
content {
associated_route_table = routing.value.associated_route_table
# Missing route map IDs
}

Read modules/site-to-site-gateway-conn/main.tf, especially the routing dynamic block around lines 52-67, and trace the inbound_route_map_id and outbound_route_map_id variables. Verify with a Terraform plan that supplied route map IDs are applied to azurerm_vpn_gateway_connection and no longer appear as drift or removal changes.

Written by the indexing model from the issue text.