Overload resolution does not prefer method that would need less conversions

[NinoFloris]

Found in #14302

type M() =
    static member A(m: int64 array, n: int64) = 1
    static member A(m: System.ReadOnlySpan<int64>, n: int64) = 2

let test() = M.A([|10L|], 1)

I would say we should prefer the first overload here instead of failing with an overload error.

https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AbEAzAzgHwBcBPABxgAIBZACgEoKBeAWACgKOLdCBDQgSzAUAtjGHAYUCgEEawkBX4A7Qqgo8oUHsTQUlC5apQNGFAIxtOXXgKGjxkmXIUBlYtzEA6AEoweAEwB5JQxiF1IeJQAeQ1QAPl19RRVUEwoAJjY2DBhCCkIYbnomak9ZAG18MwAGABl8AF1dMzogA=

[T-Gro]

The proposal is, count number of conversions per matching overload (ignoring the "kind" of conversion, nullable and others treated with same weight?). And then only if there is an overload that needs strictly less conversions then all the others, it wins ?

[T-Gro]

I am trying to think of a case where this would be counter-untuive for code reader, i.e. one where the kind of conversion should be considered stronger then a mere count.