Generating data for mailbox based on context

[EarlPitts]

Currently, data is generated in a completely random fashion for filling up the mailbox of the tested process.
This can be seen here:
https://github.com/harp-project/EquivcheckEr/blob/b33fe40b411beb7ca7c3fc541b013f4d8c5f8ae5/src/pt.erl#L83C7-L83C7
When we do the parse transform, we use PropEr with the any() type.
It's not hard to imagine that the process will not match on any of the generated data in the receive block, which will result in a timeout when comparing their return values.
A better solution would be to use the context of the receive block to guess the structure of that data, and only send messages that have the same structure.