Rule request: Forbid implicit return from closures

[iliaskarim]

New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

New rule request

Please describe the rule idea, format
this issue's title as Rule Request: [Rule Name] and describe:

1. Why should this rule be added? Share links to existing discussion about what
   the community thinks about this.
   Implicit returns from closure can be hard to read.

2. Provide several examples of what would and wouldn't trigger violations.
   Would

array.map { $0 }

Wouldn't

array.map { return $0 }

3. Should the rule be configurable, if so what parameters should be configurable?
   No configuration required

4. Should the rule be opt-in or enabled by default? Why?
   See README.md for guidelines on when to mark a rule as opt-in.
   Yes, the rule should be opt in or alternatively expressed as a configuration to the existing implicit return rule.