Fix: Add integration tests

[localheinz]

This PR

• removes useless unit tests
• removes auto-reviewtests
• turns empty unit into integration test suite
• requires symfony/filesystem as development dependency
• adds integration tests
• requires composer/composer:^1.8.0 as development dependency

Follows #117.

[codecov]

Codecov Report

Merging #129 into 1.x will decrease coverage by 26.03%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##                1.x   #129       +/-   ##
===========================================
- Coverage     26.03%     0%   -26.04%     
  Complexity       34     34               
===========================================
  Files             2      2               
  Lines           169    223       +54     
===========================================
- Hits             44      0       -44     
- Misses          125    223       +98

Impacted Files	Coverage Δ	Complexity Δ
src/NormalizePlugin.php	0% <0%> (-100%)	3% <0%> (ø)
src/Command/NormalizeCommand.php	0% <0%> (-21.88%)	31% <0%> (ø)

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[codecov]

Codecov Report

Merging #129 into 1.x will increase coverage by 51.47%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##                1.x     #129       +/-   ##
=============================================
+ Coverage     26.03%   77.51%   +51.47%     
  Complexity       34       34               
=============================================
  Files             2        2               
  Lines           169      169               
=============================================
+ Hits             44      131       +87     
+ Misses          125       38       -87

Impacted Files	Coverage Δ	Complexity Δ
src/NormalizePlugin.php	0% <0%> (-100%)	3% <0%> (ø)
src/Command/NormalizeCommand.php	81.87% <0%> (+60%)	31% <0%> (ø)	⬇️

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