[FEATURE] Display the total number of stateful links in CLI output

[niya3]

Is your feature request related to a problem? Please describe.

1. Sometime it isn't easy to get, if schemathesis recognized all it's input args. E.g. adding --stateful=link to args doesn't change the header at all.
2. It would also be very handy to print number of detected linked API operations in stateful mode (like, Collected **linked** API operations: $M) additional to current Collected API operations: $N. It would help get, if i have error with schema or some issue with schemathesis.

Describe the solution you'd like
I think it would be cool to add several lines in header printed at schemathesis run start.

Describe alternatives you've considered
Nope

Additional context
my current header:

platform Linux -- Python 3.10.1, schemathesis-3.12.3, hypothesis-6.32.1, hypothesis_jsonschema-0.22.0, jsonschema-4.3.2
rootdir: $MY_DIR
hypothesis profile 'default' -> database=DirectoryBasedExampleDatabase('/$MY_DIR/.hypothesis/examples')
Schema location: $MY_SCHEMA_FILE
Base URL: $MY_URL
Specification version: Open API 3.0.0
Workers: 1
Collected API operations: 1