Resolve pre-existing codenarc style violations

[fractalwrench]

Goal

The CodeNarc static analysis tool was added in #158 - this PR addresses pre-existing violations, where they have been simple to address. In total 16 violations have been left in the codebase with a view to addressing them as separate tickets at a later date.

Changeset

• Reduced violation count to 16, adjusted baseline accordingly
• Added @CompileStatic where changes made this possible, to gain the benefits of type-safety
• Suppressed the following overzealous checks by default:
  • InstanceOf
  • ClassJavadoc
  • ExplicitArrayListInstantiation
  • ExplicitHashSetInstantiation
  • ExplicitHashMapInstantiation
  • JavaPackageAccess
  • UnnecessaryElseStatement
  • UnnecessaryToString

Existing violations were addressed in both the main + test sourcesets. The following made up the majority of the issues:

• Use of def rather than an explicit type such as String
• Incorrect ordering of imports
• Unnecessary use of semicolon (not required in Groovy)
• Duplicate string literals
• Not using property access syntax (e.g. foo instead of getFoo())
• Unnecessary use of return keyword (not required in Groovy)

Tests

• Ran existing unit tests
• Ran existing mazerunner scenarios
• Ran ./gradlew assemble in an example Android app using Gradle 5.4.0 and AGP 3.3.0 and confirmed upload of mapping files was triggered

[fractalwrench]

There are duplicate strings in this enum constructor, but they represent different concepts and shouldn't be grouped together into one variable.

[fractalwrench]

One of the inspections was to make the caught exception less generic - I've done this where the code documents clearly what exception types can be thrown.

[fractalwrench]

create* indicates a factory method in groovy - this has been renamed to avoid a warning.

[simonbowring]

LGTM