open create form for activity/project/customer in modals

[kevinpapst]

Description

• open create forms for activity/project/customer in modals
• remove "create more" for activity and project

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I verified that my code applies to the guidelines (composer code-check)
• I updated the documentation (see here)
• I agree that this code is used in Kimai and will be published under the MIT license

[codecov]

Codecov Report

Merging #2025 into master will decrease coverage by 0.03%.
The diff coverage is 85.18%.

@@             Coverage Diff              @@
##             master    #2025      +/-   ##
============================================
- Coverage     93.33%   93.30%   -0.04%     
+ Complexity     5478     5472       -6     
============================================
  Files           518      518              
  Lines         16814    16808       -6     
============================================
- Hits          15694    15683      -11     
- Misses         1120     1125       +5     

Impacted Files	Coverage Δ	Complexity Δ
src/Form/API/ActivityApiEditForm.php	100.00% <ø> (ø)	2.00 <0.00> (ø)
src/Form/API/ProjectApiEditForm.php	100.00% <ø> (ø)	2.00 <0.00> (ø)
src/Form/ActivityEditForm.php	100.00% <ø> (ø)	8.00 <0.00> (-2.00)
src/Form/ProjectEditForm.php	100.00% <ø> (ø)	7.00 <0.00> (-2.00)
src/Controller/ActivityController.php	91.42% <84.61%> (-1.02%)	42.00 <0.00> (ø)
src/Controller/ProjectController.php	91.07% <100.00%> (-0.20%)	54.00 <0.00> (-2.00)
src/Form/EntityFormTrait.php	81.25% <0.00%> (-18.75%)	3.00% <0.00%> (ø%)