Extract method refactoring should not show full file path

[mjbvz]

TypeScript Version: 2.5.1

Code

function foo() {
    return 1 + 2;
}

highlight 1 + 2 and trigger code actions

Bug:
For the file extract, we show the entire file path:

This path can be very long and is not necessary since extract can currently only operate within the same file (at least to my knowledge).

[mhegazy]

i suppose getting the file name would be sufficient, or just saying into containing file or into this file.