Add support for multiple input directories

[gwhogg]

The detekt CLI docs indicate that multiple input directories can be supplied to it, using the -i/--input switch, provided they're delimited by commas. I've recently written a git hook which I'd like to use in conjunction with the detekt maven plugin so that only modified files are scanned by detekt. This will dramatically decrease the time it takes for pre-commit checks to happen, as the code base I'm working with is particularly large and scanning all files is a lengthy operation.

The changes here enable multiple directories to be provided. Each in turn is verified before being passed through to detekt. If any directories can't be resolved, the process is aborted and the offending paths are logged to standard out.

[codecov-commenter]

Codecov Report

Merging #203 (48eadce) into main (c10753a) will increase coverage by 0.46%.
The diff coverage is 100.00%.

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@@             Coverage Diff              @@
##               main     #203      +/-   ##
============================================
+ Coverage     73.93%   74.40%   +0.46%     
- Complexity       37       38       +1     
============================================
  Files             9        9              
  Lines           165      168       +3     
  Branches         39       40       +1     
============================================
+ Hits            122      125       +3     
  Misses           17       17              
  Partials         26       26              

Files	Coverage Δ
src/main/java/com/github/ozsie/CheckMojo.kt	94.44% <100.00%> (+1.11%)	⬆️

[Ozsie]

Code looks good, though ValidFile2.kt needs to be added to baseline.xml since there are two issues in it that we want to ignore.

/home/runner/work/detekt-maven-plugin/detekt-maven-plugin/src/test/resources/code-samples/valid2/ValidFile2.kt:1:1: Package name should match the pattern: [a-z]+(\.[a-z][A-Za-z0-9]*)* [PackageNaming]
/home/runner/work/detekt-maven-plugin/detekt-maven-plugin/src/test/resources/code-samples/valid2/ValidFile2.kt:1:1: The package declaration does not match the actual file location. [InvalidPackageDeclaration]

[gwhogg]

Code looks good, though ValidFile2.kt needs to be added to baseline.xml since there are two issues in it that we want to ignore.

/home/runner/work/detekt-maven-plugin/detekt-maven-plugin/src/test/resources/code-samples/valid2/ValidFile2.kt:1:1: Package name should match the pattern: [a-z]+(\.[a-z][A-Za-z0-9]*)* [PackageNaming]
/home/runner/work/detekt-maven-plugin/detekt-maven-plugin/src/test/resources/code-samples/valid2/ValidFile2.kt:1:1: The package declaration does not match the actual file location. [InvalidPackageDeclaration]

Thank you. I'd forgotten about the baseline, have pushed the fix in 48eadce.

[gwhogg]

@Ozsie thanks for the review. Are you happy to merge this in please, as I don't have write access.