Upgrade to Rails 7.0 and apply new framework defaults

* Remove `send_stream` method pulled in before upgrading Rails
* Remove spring, it is no longer included by default for new apps
* Remove deprecated options from environments
* Remove old asset paths and workarounds no longer needed
* Remove unnecessary `OAUTH_10_SUPPORT` const, LTI still uses OAuth 1.0
* Dump schema with new defaults (and specify precision for timestamps where needed)

bin/rails

@@ -1,5 +1,4 @@
 #!/usr/bin/env ruby
-load File.expand_path("spring", __dir__)
 APP_PATH = File.expand_path('../config/application', __dir__)
 require_relative "../config/boot"
 require "rails/commands"

bin/rake

@@ -1,5 +1,4 @@
 #!/usr/bin/env ruby
-load File.expand_path("spring", __dir__)
 require_relative "../config/boot"
 require "rake"
 Rake.application.run

bin/spring

@@ -1,14 +0,0 @@
-#!/usr/bin/env ruby
-if !defined?(Spring) && [nil, "development", "test"].include?(ENV["RAILS_ENV"])
-  gem "bundler"
-  require "bundler"
-
-  # Load Spring without loading other gems in the Gemfile, for speed.
-  Bundler.locked_gems&.specs&.find { |spec| spec.name == "spring" }&.tap do |spring|
-    Gem.use_paths Gem.dir, Bundler.bundle_path.to_s, *Gem.path
-    gem "spring", spring.version
-    require "spring/binstub"
-  rescue Gem::LoadError
-    # Ignore when Spring is not installed.
-  end
-end