Added AWS IAM data helpers

[nfx]

End-to-end example of provisioning Cross-account IAM role:

variable "account_id" {
  type        = string
  description = "External ID you find on https://accounts.cloud.databricks.com/#aws"
}

data "databricks_aws_crossaccount_policy" "this" {}
resource "aws_iam_policy" "cross_account_policy" {
  name   = "${var.prefix}-crossaccount-iam-policy"
  policy = data.databricks_aws_crossaccount_policy.this.json
}

data "databricks_aws_assume_role_policy" "this" {
    external_id = var.account_id
}

resource "aws_iam_role" "cross_account" {
  name               = "${var.prefix}-crossaccount-iam-role"
  assume_role_policy = data.databricks_aws_assume_role_policy.this.json
  description        = "Grants Databricks full access to VPC resources"
}

resource "aws_iam_role_policy_attachment" "cross_account" {
  policy_arn = aws_iam_policy.cross_account_policy.arn
  role       = aws_iam_role.cross_account.name
}

// required only in case of multiworkspace setup
resource "databricks_mws_credentials" "this" {
  provider         = databricks.mws
  account_id       = var.account_id
  credentials_name = "${var.prefix}-creds"
  role_arn         = aws_iam_role.cross_account.arn
}

[TravisBuddy]

Hey @nfx,
Your changes look good to me!

View build log

TravisBuddy Request Identifier: 5c8e3c20-e19a-11ea-81c3-ef1e647c3fbd

[codecov-commenter]

Codecov Report

Merging #255 into master will decrease coverage by 1.27%.
The diff coverage is 6.25%.

@@            Coverage Diff             @@
##           master     #255      +/-   ##
==========================================
- Coverage   62.37%   61.10%   -1.28%     
==========================================
  Files          53       54       +1     
  Lines        6374     6512     +138     
==========================================
+ Hits         3976     3979       +3     
- Misses       2066     2201     +135     
  Partials      332      332              

Impacted Files	Coverage Δ
access/data_aws_policies.go	0.00% <0.00%> (ø)
provider/provider.go	88.92% <100.00%> (+0.09%)	⬆️

[stikkireddy]

This needs a docs page

[stikkireddy]

All the other docs in the repo make a clear distinction between attribute and argument.

Argument should be user inputs where attributes are outputs/read only values computed by the resource/datasource.

This should use the naming convention

Argument reference

• <varname> - (Required/Computed/Optional) (Datatype) (content)

Attribute reference

• <varname> - (Datatype) (content)

[stikkireddy]

All the other docs in the repo make a clear distinction between attribute and argument.

Argument should be user inputs where attributes are outputs/read only values computed by the resource/datasource.

The bucket_name should be an argument where the json is an attribute.

This should use the naming convention

Argument reference

• <varname> - (Required/Computed/Optional) (Datatype) (content)

Attribute reference

• <varname> - (Datatype) (content)

[stikkireddy]

please make the following changes

[TravisBuddy]

Hey @nfx,
Your changes look good to me!

View build log

TravisBuddy Request Identifier: 0abe0730-e641-11ea-aa37-f5f007553843

[nfx]

@stikkireddy will add documentation as requested in pre-release testing branch