Ability to specify HTTP Method (GET, POST, ...) when using "newRequest" template function.

### Description

custom-api widget's go template function "newRequest" has sub functions "withHeader" and "withParameter" but has no function to specify the HTTP Method request type. I would like to add a function "withMethod" to specify the method type. The idea is to be able to do this;

```
{{
$response := newRequest ${API_URL}
| withMethod "POST"
| withParameter "paramName" "paramValue"
| getResponse
}}
```

As per the contribution's guidelines, I am making this feature request first and I intend to develop this myself. I will link the PR both here and this feature request in the PR.

Edit: [Pull Request](https://github.com/glanceapp/glance/pull/801)