Add combineLatest with multiple flows

[qwwdfsad]

• combineLatest(Iterable<Flow>) is not added deliberately, use-case is unclear
• All specific overloads are marked as inline to reduce binary compatibility pressure

Fixes #1193

[elizarov]

Very good.

[Thomas-Vos]

combineLatest(Iterable) is not added deliberately, use-case is unclear

Here is my use case for this operator:

fun <T> combineLatest(flows: Iterable<Flow<T>>): Flow<List<T>> = TODO()

// A list of connected devices.
val devices: List<Device> = getDevices()

// A list of Flows which receive the state of the device every time it changes.
val flows: List<Flow<DeviceState>> = devices.map { device ->
    device.observeState() // Flow<DeviceState>
}

// Combine the latest state of the devices into a single Flow.
val flow: Flow<List<DeviceState>> = combineLatest(flows)


// Somewhere else in the code
flow.collect { states ->
    for (state in states) {
        // TODO: do something with the states.
    }
}

[elizarov]

Please, create a separate issue.