Add UnreachableCatchBlock rule

[t-kameyama]

Fixes #305

[codecov]

Codecov Report

Merging #3478 (0cb50f3) into master (623e7fd) will decrease coverage by 0.01%.
The diff coverage is 75.00%.

@@             Coverage Diff              @@
##             master    #3478      +/-   ##
============================================
- Coverage     80.28%   80.27%   -0.02%     
- Complexity     2784     2793       +9     
============================================
  Files           454      455       +1     
  Lines          8415     8434      +19     
  Branches       1608     1614       +6     
============================================
+ Hits           6756     6770      +14     
  Misses          789      789              
- Partials        870      875       +5     

Impacted Files	Coverage Δ	Complexity Δ
...urbosch/detekt/rules/bugs/UnreachableCatchBlock.kt	72.22% <72.22%> (ø)	9.00 <9.00> (?)
...turbosch/detekt/rules/bugs/PotentialBugProvider.kt	100.00% <100.00%> (ø)	3.00 <0.00> (ø)

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[schalkms]

It might be good to add an extended description and compliant code example in order to have a better understand of the rule from the user point of view.

[t-kameyama]

0cb50f3

[schalkms]

Is this if empty check even necessary considering the any statement underneath?

[t-kameyama]

I'd like to avoid unnecessary catchClassDescriptor() call in the following case.

try {
} catch (e: Exception) {
}

[schalkms]

I like this rule 👍
Thank you!

[BraisGabin]

nice one!