[API] GQL Fetch bundle comparison for commit and pull

[JerrySentry]

Create a new resolver in Pull and Commit to fetch bundle analysis comparisons

Commit.bundleAnalysisCompareWithParent: BundleAnalysisComparisonResult
Pull.bundleAnalysisCompareWithBase: BundleAnalysisComparisonResult

union BundleAnalysisComparisonResult =
    BundleAnalysisComparison
  | FirstPullRequest
  | MissingBaseCommit
  | MissingHeadCommit
  | MissingHeadReport
  | MissingBaseReport

type BundleAnalysisComparison {
  bundles: [BundleComparison]!
  sizeDelta: Int!
  sizeTotal: Int!
  loadTimeDelta: Float!
  loadTimeTotal: Float!
}

type BundleComparison {
  name: String!
  changeType: String!
  sizeDelta: Int!
  sizeTotal: Int!
  loadTimeDelta: Float!
  loadTimeTotal: Float!
}