incoming/odfi: allow specific shards to be triggered

[adamdecaf]

On the /trigger-inbound endpoint we don't allow the option of triggering some of the shards. Instead every shard is triggered by default. We should support triggering only some shards, which is how /trigger-cutoff works.

https://github.com/moov-io/achgateway/blob/v0.15.4/internal/incoming/odfi/admin.go#L35

[adamdecaf]

@darwinz you mentioned wanting to do this change as well. Do you still want to? It should be much less code/work than adding the slack alerter.

[darwinz]

@darwinz you mentioned wanting to do this change as well. Do you still want to? It should be much less code/work than adding the slack alerter.

Yeah, I'll take this one too @adamdecaf . Thanks for checking!