feat(pos): Total item qty field to POS screen

[nemesis189]

Description:

• Similar to Grand Total, a field Total Item Qty added to display total number of items in the cart

  

no-docs

[codecov]

Codecov Report

Merging #28331 (19c62a2) into develop (9c17052) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop   #28331      +/-   ##
===========================================
+ Coverage    55.19%   55.25%   +0.06%     
===========================================
  Files         1255     1119     -136     
  Lines        67877    66667    -1210     
===========================================
- Hits         37465    36838     -627     
+ Misses       30412    29829     -583     

Impacted Files	Coverage Δ
...ype/pos_invoice_merge_log/pos_invoice_merge_log.py	75.92% <100.00%> (+1.02%)	⬆️
...eport/item_variant_details/item_variant_details.py	31.32% <0.00%> (-53.20%)	⬇️
...work_order_stock_report/work_order_stock_report.py	50.00% <0.00%> (-50.00%)	⬇️
...pnext/agriculture/doctype/fertilizer/fertilizer.py	57.14% <0.00%> (-5.36%)	⬇️
erpnext/utilities/activation.py	14.28% <0.00%> (-4.64%)	⬇️
...s/doctype/promotional_scheme/promotional_scheme.py	91.36% <0.00%> (-4.64%)	⬇️
erpnext/education/doctype/article/article.py	38.46% <0.00%> (-4.40%)	⬇️
erpnext/controllers/print_settings.py	15.78% <0.00%> (-4.22%)	⬇️
erpnext/setup/doctype/party_type/party_type.py	54.54% <0.00%> (-3.79%)	⬇️
..._scorecard_standing/supplier_scorecard_standing.py	60.00% <0.00%> (-3.64%)	⬇️
... and 1192 more