Place parameters on a new line for very long member definitions

[nojaf]

Issue created from fantomas-ui

To align more with the fix of #495, I propose to put the parameters on the next line.

Code

type C () =
    member __.LongMethodWithLotsOfParameters(aVeryLongType: AVeryLongTypeThatYouNeedToUse, aSecondVeryLongType: AVeryLongTypeThatYouNeedToUse, aThirdVeryLongType: AVeryLongTypeThatYouNeedToUse) =  aVeryLongType aSecondVeryLongType aThirdVeryLongType

Result

type C() =
    member __.LongMethodWithLotsOfParameters(aVeryLongType: AVeryLongTypeThatYouNeedToUse,
                                             aSecondVeryLongType: AVeryLongTypeThatYouNeedToUse,
                                             aThirdVeryLongType: AVeryLongTypeThatYouNeedToUse) =
        aVeryLongType aSecondVeryLongType aThirdVeryLongType

Desired result

type C () =
    member __.LongMethodWithLotsOfParameters(
        aVeryLongType: AVeryLongTypeThatYouNeedToUse
        aSecondVeryLongType: AVeryLongTypeThatYouNeedToUse
        aThirdVeryLongType: AVeryLongTypeThatYouNeedToUse)
        =
        aVeryLongType aSecondVeryLongType aThirdVeryLongType

Options

Fantomas Next - 3.3.0-3/6/2020

Name	Value
IndentOnTryWith	false
IndentSpaceNum	4
KeepNewlineAfter	false
MaxIfThenElseShortWidth	40
PageWidth	120
ReorderOpenDeclaration	false
SemicolonAtEndOfLine	false
SpaceAfterComma	true
SpaceAfterSemicolon	true
SpaceAroundDelimiter	true
SpaceBeforeArgument	true
SpaceBeforeColon	false
SpaceBeforeSemicolon	false
StrictMode	false

[nojaf]

Both the F# style guide and the G-Research style guide have this slightly different than how Fantomas does it today.

I would favour the G-Research guide here as the only difference is having the = on an extra line and the would be more consistent with how long let bindings are formatted.