Fix CS - do not import classes without namespace

[mvorisek]

• fix tests broken by added demos/db.env.php file.

[codecov]

Codecov Report

Merging #1072 into develop will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@              Coverage Diff              @@
##             develop    #1072      +/-   ##
=============================================
- Coverage      71.85%   71.82%   -0.03%     
  Complexity      2653     2653              
=============================================
  Files            126      126              
  Lines           6178     6180       +2     
=============================================
  Hits            4439     4439              
- Misses          1739     1741       +2     

Impacted Files	Coverage Δ	Complexity Δ
src/App.php	81.84% <100.00%> (ø)	137.00 <6.00> (ø)
src/ItemsPerPageSelector.php	66.66% <0.00%> (-2.30%)	11.00% <0.00%> (ø%)
src/TableColumn/Generic.php	83.67% <0.00%> (-0.87%)	38.00% <0.00%> (ø%)

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