Removed extension capsule

No longer needed now that we use exchanges which capture both the request, reponse, and any associated errors.

Issue: 261
Milestone: minor

app/aspects/extensions/capsule.rb

@@ -1,18 +0,0 @@
-# frozen_string_literal: true
-
-module Terminus
-  module Aspects
-    module Extensions
-      # A capsule of content and errors.
-      Capsule = Data.define :content, :errors do
-        def initialize content: {}, errors: {}
-          super
-        end
-
-        def clear = members.each { public_send(it).clear }
-
-        def errors? = errors.any?
-      end
-    end
-  end
-end

spec/app/aspects/extensions/capsule_spec.rb

@@ -1,33 +0,0 @@
-# frozen_string_literal: true
-
-require "hanami_helper"
-
-RSpec.describe Terminus::Aspects::Extensions::Capsule do
-  subject(:capsule) { described_class.new }
-
-  describe "#initialize" do
-    it "answers defaults" do
-      expect(capsule).to eq(described_class[content: {}, errors: {}])
-    end
-  end
-
-  describe "#clear" do
-    it "clears all members" do
-      capsule = described_class[content: {a: 1}, errors: {"test" => "Danger!"}]
-      capsule.clear
-
-      expect(capsule).to eq(described_class.new)
-    end
-  end
-
-  describe "#errors?" do
-    it "answers true when errors exist" do
-      capsule.errors["test"] = "Danger!"
-      expect(capsule.errors?).to be(true)
-    end
-
-    it "answers false when errors don't exist" do
-      expect(capsule.errors?).to be(false)
-    end
-  end
-end