Allow to define custom router name generator for play server

[yarosman]

Current operation name are transformed play.api.routing.HandlerDef.path to predefined format and you can't change it

/foo/user/$user<regexp>/blah to /foo/user/user/blah

And now you can define custom operation name generator with format like in the micrometer, and you will have the same template format between java/scala services

/foo/user/$user<regexp>/blah to /foo/user/{user}/blah instead of /foo/user/user/blah

[SimunKaracic]

Hello, please add a small writeup of what this PR is trying to achieve, and I'll get to checking out the PR soon!

[yarosman]

Hello, please add a small writeup of what this PR is trying to achieve, and I'll get to checking out the PR soon!

@SimunKaracic I added description )

[yarosman]

@SimunKaracic did you have time to review this pr ?

[SimunKaracic]

Not yet, we'll get to it this week!

[ivantopo]

Thanks a lot @yarosman!