Add support for 'view own submission' permission and anonymous submissions.

Follow-up to #2863425: Anonymous view own submission

Problem/Motivation

Anonymous submissions can be track via $_SESSION. This will user limits to be tracked and saved anonymous submissions converted to authenticated submission after a user logs in.

Proposed resolution

Add support for 'view own submission' permission and anonymous submissions.

Remaining tasks

• Never convert confidential anonymous submissions to authenticated submissions
• Add 'view own permission' to webform.permissions.yml.
• Remove comment about 'view own permission''
• Add 'Anonymous' role to Webform Access tab view/update/delete own.
• Add $check_session parameter to allow WebformSubmission query methods. Default to FALSE. This will help to clearing indicate when $_SESSION is meant to be used.
• Add WebformSubmissionStorage::setQueryConditions()
• Update \Drupal\webform\Entity\Webform::checkAccessRules
• Update WebformSubmissionStorage::setAnonymousSubmission
• Refactor account based queries to $_SESSION
• WebformSubmissionStorage::getTerminusSubmission
• WebformSubmissionStorage::getSiblingSubmission
• WebformSubmissionStorage::getMaxSubmissionId
• WebformSubmissionStorage::getTotal
• Update 'session' context to check submission 'view own' access.
• Add WebformTestBase::updateAnonymousUser
• Check \Drupal\webform\WebformSubmissionForm::checkUserLimit

Tests

• Anonymous user limits based $_SESSION.
• Anonymous user view previous.

New Premissions

• 'view own webform submission':
• 'edit any webform submission':
• 'edit own webform submission':
• 'delete any webform submission':
• 'delete own webform submission':

API changes

Session tracking will be added to the WebformSubmissionManager.