Add $view.swapLayer() API merge --wipe option and uses the option in view.merge

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 98.78049% with 1 line in your changes missing coverage. Please review.

Project coverage is 96.74%. Comparing base (af15982) to head (89bf756).

Files	Patch %	Lines
synapse/lib/storm.py	97.29%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #3828 +/- ## ========================================== - Coverage 96.81% 96.74% -0.08% ========================================== Files 241 241 Lines 52906 52973 +67 ========================================== + Hits 51221 51248 +27 - Misses 1685 1725 +40 ``` | [Flag](https://app.codecov.io/gh/vertexproject/synapse/pull/3828/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vertexproject) | Coverage Δ | | |---|---|---| | [linux](https://app.codecov.io/gh/vertexproject/synapse/pull/3828/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vertexproject) | `96.74% <98.78%> (+<0.01%)` | :arrow_up: | | [linux_replay](https://app.codecov.io/gh/vertexproject/synapse/pull/3828/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vertexproject) | `?` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vertexproject#carryforward-flags-in-the-pull-request-comment) to find out more.

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