Fix issues with user's teams not set properly and update user's roles

[pengux]

This PR fixes 2 issues:

1. Teams in the user's resource not set properly, related to r/pagerduty_escalation_policy: correctly set teams #129
2. Fix acceptance tests not passing because of updated list of user roles

Acceptance test

TF_ACC=1 go test -run TestAccPagerDutyUser_Basic ./pagerduty -v -timeout 120m
=== RUN   TestAccPagerDutyUser_Basic
--- PASS: TestAccPagerDutyUser_Basic (18.44s)
PASS
ok      github.com/terraform-providers/terraform-provider-pagerduty/pagerduty   18.468s

TF_ACC=1 go test -run TestAccPagerDutyTeamMembership_Basic ./pagerduty -v -timeout 120m
=== RUN   TestAccPagerDutyTeamMembership_Basic
--- PASS: TestAccPagerDutyTeamMembership_Basic (16.71s)
PASS
ok      github.com/terraform-providers/terraform-provider-pagerduty/pagerduty   16.746s

Step to reproduce the issue:

Using terraform

Example HCL

resource "pagerduty_user" "foo" {
  name = "Foo"
  email = "foo@foo.com"
  teams = ["${pagerduty_team.foo.id}"]
}

resource "pagerduty_team" "foo" {
  name        = "Foo"
  description = "foo"
}

Setup user and team in Pagerduty based on the configuration from the HCL above.
Import the terraform HCL above with terraform import
Doing a terraform plan now shows a difference where the team information was not imported

[heimweh]

Hi @pengux,
thank you so much for this 🙏

This LGTM 👍