Respect useLineBreaks for union/intersect toString

[JohnnyMorganz]

This change makes Luau::toString() on a union or interesection type respect the useLineBreaks option in ToStringOption.

This mostly comes up in large function type intersections. For example for the type of game:GetService:

((self: ServiceProvider, service: "ABTestService") -> ABTestService) & ((self: ServiceProvider, service: "AdService") -> AdService) & ((self: ServiceProvider, service: "AnalyticsService") -> AnalyticsService) & ((self: ServiceProvider, service: "AnimationClipProvider") -> AnimationClipProvider) & ((self: ServiceProvider, service: "AnimationFromVideoCreatorService") -> AnimationFromVideoCreatorService) & ((self: ServiceProvider, service: "AnimationFromVideoCreatorStudioService") -> AnimationFromVideoCreatorStudioService)... <TRUNCATED>

Is now formatted as

((self: ServiceProvider, service: "ABTestService") -> ABTestService)
& ((self: ServiceProvider, service: "AdService") -> AdService)
& ((self: ServiceProvider, service: "AnalyticsService") -> AnalyticsService)
& ((self: ServiceProvider, service: "AnimationClipProvider") -> AnimationClipProvider)
& ((self: ServiceProvider, service: "AnimationFromVideoCreatorService") -> AnimationFromVideoCreatorService)
& ((self: ServiceProvider, service: "AnimationFromVideoCreatorStudioService") -> AnimationFromVideoCreatorStudioService)... <TRUNCATED>

Which makes this much nicer to read.
The equivalent is done for union operations.

Example when used in VSCode hover string

I realise that I think this toString operation is used internally for Studio's hover string. So I understand if this is undesirable behaviour / conflicts with studio internally (given that its the introduction of a lot more vertical space).

[JohnnyMorganz]

I'm also interested in slightly modifying the output of TableTypeVar's when using useLineBreaks
Currently a newline is not inserted after the opening brace and before the first field (and similarly after the last field and before the closing brace).

Would you be happy accepting a change to this upstream? Again I realise its an introduction of a bit more vertical space. Will open a PR if so

Example of a before and after

local ATM: { Destroy: (self: any) -> (...any),
    __index: any,
    new: (base: any, store: any) -> (...any) }

will be modified to look like:

local ATM: {
    Destroy: (self: any) -> (...any),
    __index: any,
    new: (base: any, store: any) -> (...any)
}

[andyfriesen]

Some exceedingly nitpicky formatting minutiae. No other problems.

Thanks!