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

[ShahanaFarooqui]

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

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