feat: ledger merger

[rtdany10]

Ledger Merge aims to simplify the merging process of different accounts under the same root.
Current workflow is to open each account, click on the button, input the name and then merge.
This PR introduces a new doctype that lets the user easily merge multiple accounts.

Ledger.Merger.mp4

• Ledger Merge doctype
• Progress bar
• Tests
• Documentation

#no-docs (temp)

[codecov]

Codecov Report

Merging #28812 (321730a) into develop (56b9ad8) will decrease coverage by 0.07%.
The diff coverage is 71.42%.

@@             Coverage Diff             @@
##           develop   #28812      +/-   ##
===========================================
- Coverage    55.68%   55.61%   -0.08%     
===========================================
  Files         1129     1131       +2     
  Lines        67471    67513      +42     
===========================================
- Hits         37574    37550      -24     
- Misses       29897    29963      +66     

Impacted Files	Coverage Δ
...next/accounts/doctype/ledger_merge/ledger_merge.py	69.23% <69.23%> (ø)
...ype/ledger_merge_accounts/ledger_merge_accounts.py	100.00% <100.00%> (ø)
...eport/item_variant_details/item_variant_details.py	31.32% <0.00%> (-53.02%)	⬇️
erpnext/utilities/product.py	14.70% <0.00%> (-35.30%)	⬇️
erpnext/shopping_cart/product_info.py	30.30% <0.00%> (-21.22%)	⬇️
...eorder_level/itemwise_recommended_reorder_level.py	90.56% <0.00%> (-3.78%)	⬇️
.../report/bom_operations_time/bom_operations_time.py	93.33% <0.00%> (-3.34%)	⬇️
erpnext/assets/doctype/asset/depreciation.py	84.93% <0.00%> (-2.74%)	⬇️
...value/warehouse_wise_item_balance_age_and_value.py	92.40% <0.00%> (-2.54%)	⬇️
...e/shopping_cart_settings/shopping_cart_settings.py	65.38% <0.00%> (-1.93%)	⬇️
... and 23 more