Add a feature to split based on the tags

First of all, thank you for this wonderful plugin.

Addition to splitting all the features files in the integration folder, adding a filter to it using tags will reduce the files for execution.

In our project, we have more than 250 cases. Kind of huge of feature files. We have split the CI Jobs based on the tags and running it. But that too take a more than 2 hours to complete the execution. If this plugin provide the tags config, then we can split even more in running and get the results a bit sooner.

Am thinking of some thing like below.

npx cypress run -e tags=@test,split=true

Start by tracing how the plugin discovers and splits feature files in the integration folder, then inspect how Cypress values passed through `npx cypress run -e tags=@test,split=true` are exposed. Define the tag-selection behavior and verify that tagged cases are distributed correctly across CI jobs.

Written by the indexing model from the issue text.