Add start/end time filtering for `bkpr_accountevents` and `listforwards` like `bkpr-listincome`

Currently, the `bkpr-listincome` command supports `start_time` and `end_time` parameters for filtering records within a specific time range. However, this filtering is missing from:

1. `bkpr_accountevents` command
2. `listforwards` command

This makes it difficult to analyse time-specific accounting data and forwarding history without manually filtering the output.

### Example Usage

```bash
lightning-cli bkpr_accountevents -k start_time=1743445800 end_time=1746037799
lightning-cli listforwards -k start_time=1743445800 end_time=1746037799
```