Add weak_computed_property rule

[marcelofabri]

Fixes #2596

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[jpsim]

We really ought to simplify the boilerplate for corrections since the implementation is nearly always the same or very close to this pattern.

[marcelofabri]

We really ought to simplify the boilerplate for corrections since the implementation is nearly always the same or very close to this pattern.

Totally agreed. I will try to come up with something when I have some free time.