feat: REQ filter validation

[frnandu]

Evaluating strfry as a NWC relay alternative implementation we need such validation of REQ filters

  filterValidation {
        ## Example: Strict NWC relay configuration (similar to Alby's relay)
        enabled = true
        maxFiltersPerReq = 3
        minFiltersPerReq = 1
        maxKindsPerFilter = 3
        allowedKinds = "13194,23194,23195,23196,23197"
        requireAuthorOrTag = true
    }
  

[dskvr]

@frnandu every one of these filter validations can be achieved with plugins.

[frnandu]

@frnandu everyone one of these filter validations can be achieved with plugins.

AFAIK plugins are only for event writing policies, not for REQuests filters.

[dskvr]

Ah, yeah, you're right 👍