feat(functions): Add task queue API support (firebase#770)

* feat(functions): Add task queue API support (firebase#751) * Draft implementation of task queue * fix lint * Error handling, code review fixes and typos * feat(functions): Add unit and integration tests for task queue api support (firebase#764) * Unit and Integration tests for task queues. * fix: copyright year * fix: remove commented code * feat(functions): Added `uri` task option and additional task queue test coverage (firebase#767) * feat(functions): Add task queue API support (firebase#751) * Draft implementation of task queue * fix lint * Error handling, code review fixes and typos * feat(functions): Add unit and integration tests for task queue api support (firebase#764) * Unit and Integration tests for task queues. * fix: copyright year * fix: remove commented code * feat(functions): Added `uri` task option and additional task queue test coverage * Removed uri and add doc strings * fix removed typo * re-add missing uri changes * fix missing check * fix: TW requested changes * fix: Added extra note for full list of replaced headers and undo Content-Type change

Author: jonathanedey