Rename some pipeline and build related entities

[ci skip]

app/serializers/build_action_entity.rb

@@ -1,4 +1,4 @@
-class PipelineActionEntity < Grape::Entity
+class BuildActionEntity < Grape::Entity
   include RequestAwareEntity
 
   expose :name do |build|

app/serializers/build_artifact_entity.rb

@@ -1,4 +1,4 @@
-class PipelineArtifactEntity < Grape::Entity
+class BuildArtifactEntity < Grape::Entity
   include RequestAwareEntity
 
   expose :name do |build|

app/serializers/pipeline_entity.rb

@@ -20,9 +20,9 @@ class PipelineEntity < Grape::Entity
 
     expose :duration
     expose :finished_at
-    expose :stages, using: PipelineStageEntity
-    expose :artifacts, using: PipelineArtifactEntity
-    expose :manual_actions, using: PipelineActionEntity
+    expose :stages, using: StageEntity
+    expose :artifacts, using: BuildArtifactEntity
+    expose :manual_actions, using: BuildActionEntity
   end
 
   expose :flags do

app/serializers/stage_entity.rb

@@ -1,4 +1,4 @@
-class PipelineStageEntity < Grape::Entity
+class StageEntity < Grape::Entity
   include RequestAwareEntity
 
   expose :name

spec/serializers/build_action_entity_spec.rb

@@ -1,6 +1,6 @@
 require 'spec_helper'
 
-describe PipelineActionEntity do
+describe BuildActionEntity do
   let(:build) { create(:ci_build, name: 'test_build') }
 
   let(:entity) do

spec/serializers/build_artifact_entity_spec.rb

@@ -1,6 +1,6 @@
 require 'spec_helper'
 
-describe PipelineArtifactEntity do
+describe BuildArtifactEntity do
   let(:build) { create(:ci_build, name: 'test:build') }
 
   let(:entity) do