Use correct configuration for Skaffold dependencies

[lightoze]

Because configurations were changed in Gradle 5, existing implementation fails to detect dependencies between project modules.

[lightoze]

@googlebot I signed it!

[chanseokoh]

Awesome! Very cool to see you dug into this far.

[chanseokoh]

@lightoze in this class, there's another use of getByName("runtime") for SNAPSHOT, non-project dependencies. Does it need to be changed as well?

    for (File file : project.getConfigurations().getByName("runtime")) {
      if (!projectDependencyJars.contains(file) && file.toString().contains("SNAPSHOT")) {

And you said this is broken with Gradle 5. After changing this, will it continue to work with Gradle 4.9? (Gradle 4.9 is the minimum version Jib supports/requires.)

@loosebazooka looks like the value is now changed to "runtimeClasspath" from "runtime." Does this make sense?

[lightoze]

@chanseokoh probably that should be changed too, but it does not affect the project I have on hands so I have nothing to test on. As such "runtime" is deprecated and should be used if only for compatibility.
Gradle 4 should continue to work but I haven't tested.

[loosebazooka]

Yeah I think with 2.0 we plan on going to minimum of gradle 5 anyway: #2140

[loosebazooka]

Also, yeah I agree we should use runtimeClasspath everywhere...

[lightoze]

@chanseokoh @loosebazooka OK changed that too and reworked patch into a single commit.

[chanseokoh]

Great! Thanks for fixing this.

[chanseokoh]

I'll temporarily override the kokoro-macos failure (due to #2189) and merge this.