[datadog_integration_aws_event_bridge] Add support for AWS Event Bridge integration

[skarimo]

What does this PR do?

Adds support for a datadog_integration_aws_event_bridge terraform resource that allows users to import, create, and delete AWS EventBridge event source resources in their Datadog integration config.

Who will it impact?

Orgs using the AWS EventBridge integration to manage event sources will be able to imprort, create, and delete those with Terraform.

Motivation

https://datadoghq.atlassian.net/browse/AWSMC-706

Testing

Tested manually in my sandbox org + sandbox AWS using this config

# terraform_examples/main.tf
terraform {
  required_providers {
    datadog = {
      source = "DataDog/datadog"
    }
  }
}

provider "datadog" {
  api_key = "***"
  app_key = "***"
}

# Create a new Datadog - Amazon Web Services integration
resource "datadog_integration_aws" "sandbox" {
  account_id  = "012345678901"
  role_name   = "datadog-aws-integration-role-katie"
  filter_tags = ["key:value"]
  host_tags   = ["key:value", "key2:value2"]
}

resource "datadog_integration_aws_event_bridge" "foo" {
  account_id           = "012345678901"
  create_event_bus = true
  event_generator_name = "test7009647276"
  region               = "us-east-1"
}

Passed acceptance tests, but create_event_bus = true is not working in tests, I believe because of a missing IAM permission but I'm not sure. Will ask tf team what they think or if this should even be covered in the test.

❯ TESTARGS="-run TestAccIntegrationAwsEventBridgeBasic" make testacc
gotestsum --version || go install gotest.tools/gotestsum@latest
gotestsum version dev
which goimports || go install golang.org/x/tools/cmd/goimports@latest
/Users/katie.mckew/go/bin/goimports
RECORD=false TF_ACC=1 gotestsum --format testname --debug --rerun-fails --packages ./... -- -v -run TestAccIntegrationAwsEventBridgeBasic -timeout 120m
exec: [go test -json -v -run TestAccIntegrationAwsEventBridgeBasic -timeout 120m ./...]
go test pid: 12180
EMPTY .
EMPTY datadog
EMPTY datadog/fwprovider
EMPTY datadog/internal/fwutils (cached)
EMPTY datadog/internal/planmodifiers
EMPTY datadog/internal/utils (cached)
EMPTY datadog/internal/validators (cached)
2023/12/21 17:28:15 DD_AGENT_HOST is not configured. Tests are executed without tracer and profiler.
PASS datadog/tests.TestAccIntegrationAwsEventBridgeBasic (1.50s)
EMPTY version
PASS datadog/tests (cached)

DONE 1 tests in 2.148s

[buraizu]

Requesting some minor doc edits, but overall LGTM and approving