(Feature request) Make mocked model to_s more elegant

Current behaviour:

m = mock_model(Transaction)
m.to_s # Returns something like Transaction_#<RSpec::ExampleGroups::0x00564be9720728>

I would like to_s to also show what is stubbed inside that model, so that the spec is easier to read. For example:

m = mock_model(Transaction, type: :transfer)
m.to_s # Transaction(type: :transfer) #<RSpec::ExampleGroups::0x00564be9720728>

it { is_expected.to be_able_to(:read, mock_model(Transaction, type: :transfer)) }
# Output: It should be able to read Transaction(type: :transfer) #<RSpec::ExampleGroups::0x00564be9720728>

It will look similar to what ActiveRecord does. What do you think?

Start by locating the mock_model implementation in rspec-activemodel-mocks and inspect how its to_s output is generated. Use the Transaction examples in the issue to define the expected representation, then add coverage showing stubbed attributes in the output and confirm existing output remains intact.