Function resolveBuilderDefinition

resolveBuilderDefinition(
context: ConsoleContext,
event: IncomingEvent,
): StoneBuilderDefinition
Find the target for this run.

Precedence, and the reason for each step: the --target flag wins, because it is the most explicit thing anyone can say; then stone.builder.target, because a project that only ever builds one way should not repeat it; then detection, so a fresh application needs no configuration at all. Exactly the order the CLI used when the two targets were hard-coded.
Parameters
- context: ConsoleContext
  The console context.
- event: IncomingEvent
  The console event, carrying the flags.
Returns StoneBuilderDefinition
The definition to drive.

Throws
When the requested target is not registered, or nothing matches.