feat(alerts): adds support for signal_seasonality for NRQL baseline conditions

[akane0915]

Description

• Adds support for signal_seasonality for baseline NRQL conditions
• See ticket: https://new-relic.atlassian.net/browse/NR-368788

Related to Go Client PR

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

Checklist:

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• My commit message follows conventional commits
• My code is formatted to Go standards
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes. Go here for instructions on running tests locally.

How to test this change?

Please describe how to test your changes. Include any relevant steps in the UI, HCL file(s), commands, etc

• Try creating a newrelic_nrql_alert_condition of type baseline.
• Ensure you can set signal_seasonality successfully.
• Ensure you can null out signal_seasonality.

E.g.

resource "newrelic_nrql_alert_condition" "baseline_condition" {
  account_id                   = 400304
  policy_id                    = 1514915
  type                         = "baseline"
  name                         = "Baseline Condition from Terraform"
  enabled                      = false
  violation_time_limit_seconds = 3600
  baseline_direction           = "upper_only"
  nrql {
    query = "SELECT average(duration) FROM Transaction"
  }
  critical {
    operator              = "above"
    threshold             = 1
    threshold_duration    = 300
    threshold_occurrences = "all"
  }
  aggregation_window = 60
  aggregation_method = "event_flow"
  aggregation_delay  = 120
  fill_option        = "static"
  fill_value         = 1
  signal_seasonality = "daily"
}