Add Option.sequenceTask and Option.traverseTask + various permutations

[tw0po1nt]

Is your feature request related to a problem? Please describe.

The Option module includes traverse and sequence operations for use with Async (per #298), but not Task. Since the prevailing wisdom for F# code going forward seems to be "prefer Task", having these functions would encourage that choice.

Describe the solution you'd like
I'd like the following functions implemented in the Option module:

// traverseTask: ('a -> Task<'b>) -> 'a option -> Task<'b option>
// sequenceTask:  Task<'a> option -> Task<'a option>

Additionally, some other permutations that would be useful:

To match functions added in #321

// traverseTaskResult: ('a -> Task<Result<'b,'c>>) -> 'a option -> Task<Result<'b option, 'c>>
// sequenceTaskResult:  Task<Result<'a, 'e>> option -> Task<Result<'a option>, 'e>

It could also be useful to have permutations that work with IcedTasks, such as:

// traverseCancellableTaskResult: ('a -> CancellableTask<Result<'b,'c>>) -> 'a option -> CancellableTask<Result<'b option, 'c>>
// sequenceCancellableTaskResult:  CancellableTask<Result<'a, 'e>> option -> CancellableTask<Result<'a option>, 'e>

Since there are a potentially large amount of possible permutations, I'm partial to breaking this into a few issues / PRs, but this at least gets the conversation started.

Describe alternatives you've considered
Custom extensions in each codebase that needs these functions