codegen: Adds smithy-cli dependency to prevent auto use of smithy-cli 1.16 (#1552)

Fixes the SDK's code generation to pin smithy-cli to $smithyVersion to
restrict the supported version.

Author: jasdel

codegen/protocol-test-codegen/build.gradle.kts

@@ -17,6 +17,16 @@ import software.amazon.smithy.gradle.tasks.SmithyBuild
 
 val smithyVersion: String by project
 
+buildscript {
+    val smithyVersion: String by project
+    repositories {
+        mavenCentral()
+    }
+    dependencies {
+        "classpath"("software.amazon.smithy:smithy-cli:$smithyVersion")
+    }
+}
+
 plugins {
     id("software.amazon.smithy") version "0.5.3"
 }

codegen/sdk-codegen/build.gradle.kts

@@ -19,9 +19,15 @@ import software.amazon.smithy.model.shapes.ServiceShape
 import software.amazon.smithy.gradle.tasks.SmithyBuild
 import software.amazon.smithy.aws.traits.ServiceTrait
 
+val smithyVersion: String by project
+
 buildscript {
     val smithyVersion: String by project
+    repositories {
+        mavenCentral()
+    }
     dependencies {
+        "classpath"("software.amazon.smithy:smithy-cli:$smithyVersion")
         "classpath"("software.amazon.smithy:smithy-aws-traits:$smithyVersion")
     }
 }