Parse the GET /rest/api/3/mypreferences endpoint

[ctreminiom]

Is your feature request related to a problem? Please describe.
Right now, the library doesn't support the ability to manipulate the Jira Myself endpoints, please create a new implementation of it.

Describe the solution you'd like
Please implement the Get method on the MySelfConnector interface.

Describe the tasks needed

• Under the MySelfConnector interface, create the method Get with the corresponding documentation (comments).
• Edit the file jira/internal/myself_impl.go and create the Get implementation (please use the other service as a reference).
• Create the unit test cases with a minimum of 80% of coverage.

Additional context

• https://developer.atlassian.com/cloud/jira/platform/rest/v3/api-group-myself/#api-rest-api-3-mypreferences-get