Change user password

### Support reference number

### Description

Documentation states that customersPassword is implemented, but code suggestions say otherwise, and error shows up in code.


Geeting the error:
```
_commercetools_client__WEBPACK_IMPORTED_MODULE_0__.requestBuilder.customersPassword is not a function
```

Code used:
```js
await requestBuilder
.customersPassword()
.post({
body: {
id: id,
version: version,
currentPassword: 'old',
newPassword: 'new'
}
})
.execute()
```

Packages in use:
```js
"@commercetools/sdk-auth": "^3.0.12",
"@commercetools/sdk-client": "^2.1.2",
"@commercetools/sdk-middleware-auth": "^6.1.4",
"@commercetools/sdk-middleware-http": "^6.0.11",
```

### Expected Behavior

If implemented it should work

### Current Behavior

See description above.

### Context

Password change. Currently blocking our work since it seems there is no way to change it other than making a direct REST call, which is less than ideal.

### Possible Solution