[Feature] Add databricks_budget resource

[840]

Changes

Add support for account-level Budget resource

Example structure

resource "databricks_budget" "this" {
    display_name = "data-science-budget"

    alert_configurations {
        time_period         = "MONTH"
        trigger_type        = "CUMULATIVE_SPENDING_EXCEEDED" 
        quantity_type       = "LIST_PRICE_DOLLARS_USD"
        quantity_threshold  = "840"

        action_configurations {
            action_type = "EMAIL_NOTIFICATION"
            target      = "me@databricks.com"
        }
    }

    filter {
        workspace_id {
            operator = "IN"
            values   = [
                1234567890098765
            ]                              
        }
        tags {
            key   = "Databricks"
            value {
                operator = "IN"
                values = ["Data Science"]
            }
        }
    }
}

Resolves #3887

Tests

• make test run locally
• relevant change in docs/ folder
• covered with integration tests in internal/acceptance
• relevant acceptance tests are passing
• using Go SDK

[alexott]

Can we ask the product team why quantity_threshold is string?

[alexott]

Most important comment is about AccountClientWithAccountIdFromConfig

[alexott]

code lgtm

[alexott]

I put docs into FinOps category to distinguish it from deployment-related docs

[alexott]

Integration tests are failing on GCP, although they should pass...

[alexott]

@tanmay-db can we get review for this?

[tanmay-db]

Hi @alexott , thanks for the ping, I will take a look

[tanmay-db]

Hi @840, thanks for the PR. I had some comments. Stamping the PR as they are minor comments, I have also triggered nightly tests, please don't merge the PR yet.