Replace identity in kedro telemetry with unique username

[SajidAlamQB]

Description

This is related to the heap issue. Looking at the kedro-telemetry plugin we currently assign the hashed computer name of users to the identity parameter for Heap. Having a look at the Heap API it makes more sense to assign this to something like username.

Note: The identity parameter needs to be unique, so we may want to find a way to ensure this. (Maybe we hash the concatenation of username and computer name?)

Reason for this:
Heap generates a unique userID that can't be manually changed and isn't related/mapped to the username parameter. However, if heap finds the same identity it will merge that userID into the Heap profile of the identified user.

Context

#36

[yetudada]

Thank you so much for the investigation on this @SajidAlamQB! I think this is a sensible solution for the matching the user IDs. I don't think we need to combine the hashed_username with hashed_computer_name because they're both hashed. hashed_username should be enough.