Plugin option to configure smithy-go dependency version

[tlindsay42]

When the generateGoMod setting is enabled, the smithy-go dependency is added at version v1.4.0 from way back in May 2021. It'd be nice to have an option to configure this and/or default to using the plugin version or latest.

References:

• smithy-go/codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/SmithyGoDependency.java

  Line 139 in 0681fa9

  private static final String SMITHY_GO = "v1.4.0";

• smithy-go/codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/SmithyGoDependency.java

  Line 117 in 0681fa9

  return relativePackage(SMITHY_SOURCE_PATH, relativePath, Versions.SMITHY_GO, alias);