Created Screen base class

[gbenziv]

Closes #187

• Implemented backoffice screen base class
• Moved showoptions and invalid option

Pull Request Checklist

• [x] I have ensured that my commit message contains the Issue ID.
• [x] I have ensured that my commit message contains the feature/bugfix description.
• [ ] I have updated the documentation accordingly.
• [x] I have ensured my code follows the coding guidelines.
• [x] I have ran lint in my code locally prior to submission.
• [x] I have built my changes in local successfully.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[codecov[bot]]

Codecov Report

Merging #192 (c331293) into master (30d3a67) will increase coverage by 4.55%. The diff coverage is 97.17%.

@@            Coverage Diff             @@
##           master     #192      +/-   ##
==========================================
+ Coverage   90.78%   95.33%   +4.55%     
==========================================
  Files          43       45       +2     
  Lines         792      900     +108     
==========================================
+ Hits          719      858     +139     
+ Misses         73       42      -31     

Impacted Files	Coverage Δ
...ore/domain/customermgmt/customermgmtcontroller.hpp	100.00% <ø> (ø)
core/domain/dashboard/dashboardcontroller.hpp	100.00% <ø> (ø)
core/domain/employeemgmt/employeecontroller.hpp	100.00% <ø> (ø)
core/domain/inventory/inventorycontroller.hpp	100.00% <ø> (ø)
core/domain/dashboard/dashboardcontroller.cpp	89.65% <66.66%> (ø)
core/domain/userlogin/logincontroller.cpp	92.85% <66.66%> (ø)
core/domain/inventory/inventorycontroller.cpp	94.91% <93.33%> (-0.80%)	:arrow_down:
core/domain/employeemgmt/employeecontroller.cpp	96.07% <94.11%> (-0.29%)	:arrow_down:
...ore/domain/customermgmt/customermgmtcontroller.cpp	95.77% <97.72%> (+68.27%)	:arrow_up:
core/domain/common/basecontroller.hpp	100.00% <100.00%> (ø)
... and 12 more

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