Some IAM fixes that I found necessary to add / reinstate to get the toolkit working

[Analect]

Describe the bug
Certain permissions are missing from iam.tf. It seems this PR tightened permissions available to different roles. However, I found in order to get things working, I need to reinstate some of these. I was using the deployment-scripts/quick-deploy.sh approach (rather than CodePipeline or Github Actions approaches).

To Reproduce
Steps to reproduce the behavior:

1. Run bash deployment-scripts/quick-deploy.sh
2. Initially I was getting Terraform errors akin to those raised over on this data-toolkit issue.
3. With that fix in place, the CodePipeline was failing at various points due to access-denied in various different roles, depending on which part of the pipeline you were on.

Expected behavior
That the job would run through without issue.

Additional context

These were changes I had to make back to the iam.tf file:

# under `sagemaker_role_policy`, I added back in these, since otherwise it wasn't allowing pushing back training/inference files back to S3.
"s3:Get*",
"s3:List*",
"s3:PutObject",
"s3:DeleteObject",

# under the `codepipeline_policy_document`, I added back these, as otherwise the pipeline wasn't instantiating, again for permissioning back to S3 issues.
"s3:Get*",
"s3:Put*",
"s3:List*"

I needed to add a Lambda and StepFunction section (also under  the `codepipeline_policy_document`) ... for Step Function part to work. These are hard-coded in for now, so I could get things working.

  statement {
    sid = "Lambda"

    actions = [
      "lambda:InvokeFunction"
    ]

    resources = [
      "arn:aws:lambda:eu-west-1:<account-id>:function:*"
    ]
  }

  statement {
    sid = "StepFunction"

    actions = [
      "states:StartExecution",
      "states:DescribeStateMachine",
      "states:DescribeExecution"
    ]

    resources = [
      "arn:aws:states:eu-west-1:<account-id>:stateMachine:ml-core-development-training-step-function",
      "arn:aws:states:eu-west-1:<account-id>:stateMachine:ml-core-development-inference-step-function",
      "arn:aws:states:eu-west-1:<account-id>:execution:ml-core-development-training-step-function:*",
      "arn:aws:states:eu-west-1:<account-id>:execution:ml-core-development-inference-step-function:*"
    ]
  }