Restoring Needed omitempty o RuleAction.Suppress Fields

[stmcallister]

Recent change to the RuleAction.Suppress object made it impossible to simply set the value field. This change will allow for that and also includes the suppress field in tests. This change affects both Ruleset Rules and Service Event Rules.

Ruleset Rule Test Results

TF_ACC=1 go test -run "TestAccPagerDutyRulesetRule" ./pagerduty -v -timeout 120m     
=== RUN   TestAccPagerDutyRulesetRule_import
--- PASS: TestAccPagerDutyRulesetRule_import (5.33s)
=== RUN   TestAccPagerDutyRulesetRule_Basic
--- PASS: TestAccPagerDutyRulesetRule_Basic (6.60s)
=== RUN   TestAccPagerDutyRulesetRule_MultipleRules
--- PASS: TestAccPagerDutyRulesetRule_MultipleRules (6.83s)
PASS
ok  	github.com/terraform-providers/terraform-provider-pagerduty/pagerduty	24.884s

Service Event Rule Test Results

TF_ACC=1 go test -run "TestAccPagerDutyServiceEventRule" ./pagerduty -v -timeout 120m
=== RUN   TestAccPagerDutyServiceEventRule_import
--- PASS: TestAccPagerDutyServiceEventRule_import (10.65s)
=== RUN   TestAccPagerDutyServiceEventRule_Basic
--- PASS: TestAccPagerDutyServiceEventRule_Basic (11.74s)
=== RUN   TestAccPagerDutyServiceEventRule_MultipleRules
--- PASS: TestAccPagerDutyServiceEventRule_MultipleRules (12.39s)
PASS
ok  	github.com/terraform-providers/terraform-provider-pagerduty/pagerduty	35.365s