Add method to update mocks declaratively, closes #344

[codecov[bot]]

Codecov Report

Base: 99.47% // Head: 99.47% // Increases project coverage by +0.00% :tada:

Coverage data is based on head (db0a200) compared to base (6d90452). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #345 +/- ## ========================================= Coverage 99.47% 99.47% - Complexity 681 682 +1 ========================================= Files 169 169 Lines 1524 1526 +2 Branches 87 87 ========================================= + Hits 1516 1518 +2 Misses 8 8 ``` | [Impacted Files](https://codecov.io/gh/dmfs/jems/pull/345?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Marten+Gajda) | Coverage Δ | | |---|---|---| | [...ing/src/main/java/org/dmfs/jems2/mockito/Mock.java](https://codecov.io/gh/dmfs/jems/pull/345/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Marten+Gajda#diff-amVtczItdGVzdGluZy9zcmMvbWFpbi9qYXZhL29yZy9kbWZzL2plbXMyL21vY2tpdG8vTW9jay5qYXZh) | `96.66% <100.00%> (+0.23%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Marten+Gajda). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Marten+Gajda)

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