Allow access to smithyCli configuration

[hpmellema]

Background

• Makes the smithyCli configuration visible so a customer can explicitly set the CLI artifact without setting a smithy-model dependency in the runtimeClasspath configuration (typically through the implementation configuration.

While the CLI version can be resolved from a runtime dependency on smithy-model, users sometimes want to explicitly configure a CLI artifact to use without any runtime dependencies on the smithy-model package.

Currently the best way to do this is with a build script dependency:

val smithyVersion: String by project

buildscript {
    val smithyVersion: String by project

    repositories {
        mavenLocal()
        mavenCentral()
    }
    dependencies {
        "classpath"("software.amazon.smithy:smithy-cli:$smithyVersion")
    }
}

With this change a customer can set the cli artifact as:

dependencies {
    val smithyVersion: String by project

    smithyCli("software.amazon.smithy:smithy-cli:$smithyVersion")
}

Which results in the following resolved configurations:

smithyCli - Configuration for Smithy CLI and associated dependencies.
\--- software.amazon.smithy:smithy-cli:1.45.0
     +--- software.amazon.smithy:smithy-model:1.45.0
     |    \--- software.amazon.smithy:smithy-utils:1.45.0
     +--- software.amazon.smithy:smithy-build:1.45.0
     |    +--- software.amazon.smithy:smithy-utils:1.45.0
     |    \--- software.amazon.smithy:smithy-model:1.45.0 (*)
     +--- software.amazon.smithy:smithy-diff:1.45.0
     |    +--- software.amazon.smithy:smithy-utils:1.45.0
     |    \--- software.amazon.smithy:smithy-model:1.45.0 (*)
     \--- software.amazon.smithy:smithy-syntax:1.45.0
          +--- software.amazon.smithy:smithy-model:1.45.0 (*)
          \--- software.amazon.smithy:smithy-utils:1.45.0

runtimeClasspath - Runtime classpath of source set 'main'.
No dependencies

What happens when conflicting deps are set?

If the smithy cli dependency is set in the smithyCli configuration then we will not attempt to resolve the cli artifact version from the smithy-model dependency.

If conflicting dependencies are set then the higher version is used by default unless a customer sets up a custom resolution strategy. The smithyCli configuration extends the runtimeClasspath configuration (if available) so it will use the higher version set in the runtimeClasspath configuration but the reverse will not be true.

For example the following:

dependencies {
    smithyCli("software.amazon.smithy:smithy-cli:1.45.0")
    implementation("software.amazon.smithy:smithy-cli:1.43.0")
}

Will resolve to:

smithyCli - Configuration for Smithy CLI and associated dependencies.
+--- software.amazon.smithy:smithy-cli:1.43.0 -> 1.45.0
|    +--- software.amazon.smithy:smithy-model:1.45.0
|    |    \--- software.amazon.smithy:smithy-utils:1.45.0
|    +--- software.amazon.smithy:smithy-build:1.45.0
|    |    +--- software.amazon.smithy:smithy-utils:1.45.0
|    |    \--- software.amazon.smithy:smithy-model:1.45.0 (*)
|    +--- software.amazon.smithy:smithy-diff:1.45.0
|    |    +--- software.amazon.smithy:smithy-utils:1.45.0
|    |    \--- software.amazon.smithy:smithy-model:1.45.0 (*)
|    \--- software.amazon.smithy:smithy-syntax:1.45.0
|         +--- software.amazon.smithy:smithy-model:1.45.0 (*)
|         \--- software.amazon.smithy:smithy-utils:1.45.0
\--- software.amazon.smithy:smithy-cli:1.45.0 (*)

runtimeClasspath - Runtime classpath of source set 'main'.
\--- software.amazon.smithy:smithy-cli:1.43.0
     +--- software.amazon.smithy:smithy-model:1.43.0
     |    \--- software.amazon.smithy:smithy-utils:1.43.0
     +--- software.amazon.smithy:smithy-build:1.43.0
     |    +--- software.amazon.smithy:smithy-utils:1.43.0
     |    \--- software.amazon.smithy:smithy-model:1.43.0 (*)
     +--- software.amazon.smithy:smithy-diff:1.43.0
     |    +--- software.amazon.smithy:smithy-utils:1.43.0
     |    \--- software.amazon.smithy:smithy-model:1.43.0 (*)
     \--- software.amazon.smithy:smithy-syntax:1.43.0
          +--- software.amazon.smithy:smithy-model:1.43.0 (*)
          \--- software.amazon.smithy:smithy-utils:1.43.0

While the following:

For example the following: 

dependencies {
smithyCli("software.amazon.smithy:smithy-cli:1.45.0")
implementation("software.amazon.smithy:smithy-model:1.43.0")
}

Resolves to: 

smithyCli - Configuration for Smithy CLI and associated dependencies.
+--- software.amazon.smithy:smithy-model:1.43.0 -> 1.45.0
| --- software.amazon.smithy:smithy-utils:1.45.0
--- software.amazon.smithy:smithy-cli:1.45.0
+--- software.amazon.smithy:smithy-model:1.45.0 ()
+--- software.amazon.smithy:smithy-build:1.45.0
| +--- software.amazon.smithy:smithy-utils:1.45.0
| --- software.amazon.smithy:smithy-model:1.45.0 ()
+--- software.amazon.smithy:smithy-diff:1.45.0
| +--- software.amazon.smithy:smithy-utils:1.45.0
| --- software.amazon.smithy:smithy-model:1.45.0 ()
--- software.amazon.smithy:smithy-syntax:1.45.0
+--- software.amazon.smithy:smithy-model:1.45.0 ()
--- software.amazon.smithy:smithy-utils:1.45.0

runtimeClasspath - Runtime classpath of source set 'main'.
--- software.amazon.smithy:smithy-model:1.43.0
--- software.amazon.smithy:smithy-utils:1.43.0

#### Testing
* Added a new integration test to test this behavior.

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