Remove ModifierComposable rule

[mrmans0n]

From the issue raised:

I believe this lint rule is out of date and should be removed. @composable Modifier extension functions used to be recommended against, but official documentation is currently more supportive of it: https://developer.android.com/develop/ui/compose/custom-modifiers#create_a_custom_modifier_using_a_composable_modifier_factory

@composable modifier extension functions help avoid unnecessary recompositions, compared to if you hadn't put the @composable annotation, because @composable auto-remembers lambdas from previous calls. This allows the Modifier to be considered equivalent to the previous value, and then doesn't prevent skipping because of it.

// This will always create a new Modifier that will prevent skipping, because the lambda inside is recreated on each call.
fun Modifier.myBackground(color: Color): Modifier = drawBehind { drawRect(color) }
vs

// This will return an equivalent Modifier because the lambda is automatically remembered from the previous call.
@composable
fun Modifier.myBackground(color: Color): Modifier = drawBehind { drawRect(color) }
I think a more appropriate lint would be against Modifier extension functions without the @composable annotation and could be recreating lambdas inside.

Addresses #393