feat: Leave Encashment Enhancements

[ruchamahabal]

no-docs (temp)

• Add Maximum Encashable Leaves setting in Leave Type
• Refactor: reorder function calls for correctness
• Allow overwriting encashable days
• Inform the user about the calculation based on threshold and max leaves setting
• Enable Allow on Submit for Encashment Amount in Salary Structure
• Enable Non Negative checks for settings
• Tests
• Encashment threshold functionality naming makes no sense Issue with Leave Encashment #420, fix: Leave Encashment calculations erpnext#31062 (comment)
• Rethink correlation and effect with CF leaves and existing allocation

Closes #921

Leave Type

• Added a setting for Maximum Encashable Leaves
• Renamed Encashment Threshold Days -> Non-Encashable Leaves because it indicates the number of leaves that cannot be encashed

Leave Encashment

Instead of making Encashable Days directly editable - since its value is primarily derived from the leave balance & leave type settings:

• Added Actual Encashable Days: Denotes the number of leaves eligible for encashment based on leave type settings

  • This gets auto-calculated: e.g: leave balance = 10, non-encashable leaves = 3, max encashable leaves = 5
  • Then Actual Encashable Days = 5 (10 - 3 = 7, but max is 5)

• Added Encashment Days: By default set to actual encashable days but the user can choose to overwrite this to encash less number of leaves than the actual encashable days value. Added validations and msgprints for the same

  

• Patch for setting the above fields = encashable days (old field)

[codecov-commenter]

Codecov Report

Merging #817 (8a66ce2) into develop (a8501ea) will increase coverage by 0.04%.
Report is 12 commits behind head on develop.
The diff coverage is 96.49%.

@@             Coverage Diff             @@
##           develop     #817      +/-   ##
===========================================
+ Coverage    73.83%   73.88%   +0.04%     
===========================================
  Files          195      195              
  Lines        10397    10412      +15     
===========================================
+ Hits          7677     7693      +16     
+ Misses        2720     2719       -1     

Files	Coverage Δ
...ms/hr/doctype/leave_encashment/leave_encashment.py	83.33% <97.05%> (+4.50%)	⬆️
hrms/payroll/doctype/salary_slip/salary_slip.py	86.75% <95.65%> (-0.03%)	⬇️

[ruchamahabal]

Tests passed but coverage upload failed. Merging