Expose `humanTimeEstimate` & `humanTotalTimeSpent`

Update `merge_request_type` in GraphQL to expose
`humanTimeEstimate` & `humanTotalTimeSpent`.

Changelog: added

app/graphql/types/merge_request_type.rb

@@ -162,6 +162,10 @@ module Types
           description: 'Time estimate of the merge request.'
     field :total_time_spent, GraphQL::INT_TYPE, null: false,
           description: 'Total time reported as spent on the merge request.'
+    field :human_time_estimate, GraphQL::STRING_TYPE, null: true,
+          description: 'Human-readable time estimate of the merge request.'
+    field :human_total_time_spent, GraphQL::STRING_TYPE, null: true,
+          description: 'Human-readable total time reported as spent on the merge request.'
     field :reference, GraphQL::STRING_TYPE, null: false, method: :to_reference,
           description: 'Internal reference of the merge request. Returned in shortened format by default.' do
       argument :full, GraphQL::BOOLEAN_TYPE, required: false, default_value: false,

doc/api/graphql/reference/index.md

@@ -10041,6 +10041,8 @@ Maven metadata.
 | <a id="mergerequesthasci"></a>`hasCi` | [`Boolean!`](#boolean) | Indicates if the merge request has CI. |
 | <a id="mergerequesthassecurityreports"></a>`hasSecurityReports` | [`Boolean!`](#boolean) | Indicates if the source branch has any security reports. |
 | <a id="mergerequestheadpipeline"></a>`headPipeline` | [`Pipeline`](#pipeline) | The pipeline running on the branch HEAD of the merge request. |
+| <a id="mergerequesthumantimeestimate"></a>`humanTimeEstimate` | [`String`](#string) | Human-readable time estimate of the merge request. |
+| <a id="mergerequesthumantotaltimespent"></a>`humanTotalTimeSpent` | [`String`](#string) | Human-readable total time reported as spent on the merge request. |
 | <a id="mergerequestid"></a>`id` | [`ID!`](#id) | ID of the merge request. |
 | <a id="mergerequestiid"></a>`iid` | [`String!`](#string) | Internal ID of the merge request. |
 | <a id="mergerequestinprogressmergecommitsha"></a>`inProgressMergeCommitSha` | [`String`](#string) | Commit SHA of the merge request if merge is in progress. |

spec/graphql/types/merge_request_type_spec.rb

@@ -30,8 +30,8 @@ RSpec.describe GitlabSchema.types['MergeRequest'] do
       source_branch_exists target_branch_exists diverged_from_target_branch
       upvotes downvotes head_pipeline pipelines task_completion_status
       milestone assignees reviewers participants subscribed labels discussion_locked time_estimate
-      total_time_spent reference author merged_at commit_count current_user_todos
-      conflicts auto_merge_enabled approved_by source_branch_protected
+      total_time_spent human_time_estimate human_total_time_spent reference author merged_at
+      commit_count current_user_todos conflicts auto_merge_enabled approved_by source_branch_protected
       default_merge_commit_message_with_description squash_on_merge available_auto_merge_strategies
       has_ci mergeable commits_without_merge_commits squash security_auto_fix default_squash_commit_message
       auto_merge_strategy merge_user