Issue:
fix(address): use first_name if last_name is not passed

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix

## Description
<!-- Describe your changes in detail -->
This PR fixes the issue which arises when creating a payement with cybersource and bank of america connectors where billing first name and last name are mandatory.


## Motivation and Context
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Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless it is an obvious bug or documentation fix
that will have little conversation).
-->


## How did you test it?
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Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
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- Create a payment by passing billing address in payment create request, with confirm set to false.
```bash
curl --location 'http://localhost:8080/payments' \
--header 'Content-Type: application/json' \
--header 'api-key: dev_uHrHd27n2djqmWLoWqhpHPf1NmU2dsIbEguhDIB9ji7bQmzf9rLqw9TqrsRybqwm' \
--data-raw '{
    "amount": 6540,
    "currency": "USD",
    "confirm": false,
    "customer": {
        "id": "cus_abc",
        "email": "example@juspay.in"
    },
    "billing": {
        "address": {
            "line1": "1467",
            "line2": "Harrison Street",
            "city": "San Fransico",
            "state": "California",
            "zip": "94122",
            "country": "US",
            "first_name": "Narayan",
            "last_name": "Bhat"
        }
    }
}'
```

- Confirm the payment with `card_holder_name`, by not passing last name
```bash
curl --location 'http://localhost:8080/payments/pay_QHybdDJQVMZVgS4BX4IQ/confirm' \
--header 'Content-Type: application/json' \
--header 'Accept: application/json' \
--header 'api-key: dev_uHrHd27n2djqmWLoWqhpHPf1NmU2dsIbEguhDIB9ji7bQmzf9rLqw9TqrsRybqwm' \
--data '{
    "payment_method_data": {
        "card": {
            "card_number": "4242424242424242",
            "card_exp_month": "10",
            "card_exp_year": "25",
            "card_holder_name": "Narayan",
            "card_cvc": "123"
        }
    },
    "payment_method": "card"
}'
```

## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [x] I reviewed the submitted code


Resolution:
<think>
PR Context:
- Title: fix(address): use first_name if last_name is not passed
- Merged: 2024-04-16T08:31:44Z
- Files changed: 9 files
- Commits: 1 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix

## Description
<!-- Describe your changes in detail -->
More details can be found in #4360 


## Motivation and Context
<!--
Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless it is an obvious bug or documentation fix
that w
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** fix(address): use first_name if last_name is not passed (#4367)
Files to modify:


**crates/router/src/connector/bankofamerica/transformers.rs**
  Modify existing code

**crates/router/src/connector/bluesnap/transformers.rs**
  Modify existing code

**crates/router/src/connector/cybersource/transformers.rs**
  Modify existing code

**crates/router/src/connector/forte/transformers.rs**
  Modify existing code

**crates/router/src/connector/multisafepay/transformers.rs**
  Modify existing code

**crates/router/src/connector/nmi/transformers.rs**
  Modify existing code

**crates/router/src/connector/nuvei/transformers.rs**
  Modify existing code

**crates/router/src/connector/utils.rs**
  Modify existing code

**crates/router/src/connector/volt/transformers.rs**
  Modify existing code