Add API to upload a patched build for a custom A/B testing

Add API to upload a patched build for a custom A/B testing
https://bugs.webkit.org/show_bug.cgi?id=171956

Reviewed by Chris Dumez.

Added /api/upload-root to upload a root file, the build product of a patch associated with a commit set.

Extracted more functions out of privileged-api/upload-file.php to uploaded-file-helpers.php to share code
with /api/upload-root.php.

* public/api/upload-root.php: Added.
(main):
(compute_commit_set_items_to_update): Find the list of commit set items to associate this root with.
A root can be associated with multiple repositories and there fore commit set items; e.g. if a software
is built from multiple repositories and there is a patch associated with one of them, the built product
must be associated with all those repositories.

* public/include/build-requests-fetcher.php:
(BuildRequestsFetcher::fetch_commits_for_set_if_needed): Include the root file is there is one.

* public/include/json-header.php:
(validate_arguments): Added the support for validating json string.
(verify_slave): Return the slave ID found.

* public/include/uploaded-file-helpers.php:
(validate_uploaded_file): Extracted from /privileged-api/upload-file to be shared with /api/upload-root.
(query_total_file_size): Ditto.
(create_uploaded_file_from_form_data): Ditto.
(upload_file_in_transaction): Ditto. Takes a lambda to do the extra work inside the transaction.

* public/privileged-api/upload-file.php:
(main):

* public/v3/models/build-request.js:
(BuildRequest.constructBuildRequestsFromData): Resolve the rootFIle of each commit set item.

* public/v3/models/commit-set.js:
(CommitSet): Added _repositoryToRootMap and _allRootFiles as instance variables.
(CommitSet.prototype.updateSingleton): Added. Previously, each commit set's states never changed after
its creation. After this patch, each item can be newly associated with a root so we must update its
_repositoryToRootMap and _allRootFiles. For simplicity, we update all states.
(CommitSet.prototype._updateFromObject): Extracted from the constructor.
(CommitSet.prototype.allRootFiles): Added. Includes custom roots and roots created for patches.
(CommitSet.prototype.rootForRepository): Added.
(CommitSet.prototype.equals): Fixed the bug that we were comparing _repositoryToPatchMap to
_repositoryToCommitMap, and added a check for _repositoryToRootMap.

* public/v3/models/test-group.js:
(TestGroup.prototype.task): Added.
(TestGroup.createWithTask):
(TestGroup.createWithCustomConfiguration):
(TestGroup.createAndRefetchTestGroups):
(TestGroup._fetchTestGroupsForTask): Deleted. Now fetchForTask takes a boolean argument: ignoreCache.
(TestGroup.findAllByTask): Added.
(TestGroup.fetchForTask): Renamed from fetchByTask.

* public/v3/pages/analysis-task-page.js:
(AnalysisTaskPage.prototype._fetchRelatedInfoForTaskId):

* server-tests/api-build-requests-tests.js:

* server-tests/api-upload-root-tests.js: Added. Added tests for /api/upload-root.
(makeReport): Added.
(addSlaveAndCreateRootFile): Added.
(createTestGroupWihPatch): Added.

* server-tests/privileged-api-create-test-group-tests.js:

* server-tests/resources/mock-data.js:
(MockData.sharedRepositoryId): Added.
(MockData.addMockData): Added "Shared" repository along with commits.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@216647 268f45cc-cd09-0410-ab3c-d52691b4dbfc