Fix #285 Support rich menu switch action

[gotokatsuya]

#285

[CLAassistant]

All committers have signed the CLA.

[kkdai]

@clsung Would you help to check this one?

[codecov-commenter]

Codecov Report

Merging #286 (5b3a012) into master (81a4a47) will increase coverage by 1.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #286      +/-   ##
==========================================
+ Coverage   76.82%   77.94%   +1.11%     
==========================================
  Files          36       36              
  Lines        2447     2847     +400     
==========================================
+ Hits         1880     2219     +339     
- Misses        436      497      +61     
  Partials      131      131              

Impacted Files	Coverage Δ
linebot/event.go	88.82% <ø> (+0.25%)	⬆️
linebot/richmenu.go	61.24% <ø> (+0.37%)	⬆️
linebot/message.go	78.52% <0.00%> (-3.84%)	⬇️
linebot/delivery.go	69.69% <0.00%> (-0.68%)	⬇️
linebot/emoji.go	100.00% <0.00%> (ø)
linebot/error.go	0.00% <0.00%> (ø)
linebot/leave.go	100.00% <0.00%> (ø)
linebot/sender.go	100.00% <0.00%> (ø)
linebot/insight.go	100.00% <0.00%> (ø)
linebot/progress.go	100.00% <0.00%> (ø)
... and 28 more

---

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[clsung]

Can you add some unit tests?

[gotokatsuya]

OK

[gotokatsuya]

@clsung I just add webhook test. Could you check it? Let me know if you have better test.

[clsung]

LGTM

[kkdai]

LGTM