DEV: Prepare new structure for migrations-tooling (#26631)

* Moves existing files around. All essential scripts are in `migrations/bin`, and non-essential scripts like benchmarks are in `migrations/scripts`
* Dependabot configuration for migrations-tooling (disabled for now)
* Updates test configuration for migrations-tooling
* Shorter configuration for intermediate DB for now. We will add the rest table by table.
* Adds a couple of benchmark scripts
* RSpec setup especially for migrations-tooling and the first tests
* Adds sorting/formatting to the `generate_schema` script

migrations/scripts/benchmarks/time_formatting.rb

@@ -0,0 +1,25 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "bundler/inline"
+
+gemfile(true) do
+  source "https://rubygems.org"
+  gem "benchmark-ips"
+end
+
+require "benchmark/ips"
+require "time"
+
+THE_TIME = Time.now.utc
+DATE_TIME = DateTime.now.new_offset(0)
+
+Benchmark.ips do |x|
+  x.config(time: 10, warmup: 2)
+
+  x.report("Time#iso8601") { THE_TIME.iso8601 }
+  x.report("Time#strftime") { THE_TIME.strftime("%FT%TZ") }
+  x.report("DateTime#iso8601") { DATE_TIME.iso8601 }
+
+  x.compare!
+end