fix: get incoming rate instead of BOM rate

[s-aga-r]

Issue: 0 RM rate in SCR results in incorrect FG Valuation Rate.

Steps to replicate:

• Set Backflush Raw Materials of Subcontract Based On to BOM in Buying Settings
• Create an FG Item.
• Create RM Item(s) with Valuation Rate as 0.
• Create BOM for FG Item, RM(s) will have a rate of 0 since there is no SLE/Valuation Rate.
• Create PO -> SCO
• Inward RM(s) and transfer against the SCO
• Now, create SCO -> SCR (save), the RM rate will be 0.

Changes: Set the Incoming Rate as the rate for RMs in the SCR Consumed Items table.

Before:

scrnli_8_5_2023_10-32-16.AM.mp4

After:

scrnli_8_5_2023_10-32-56.AM.mp4

[codecov]

Codecov Report

Merging #36496 (70072d7) into develop (10529e1) will increase coverage by 0.06%.
Report is 60 commits behind head on develop.
The diff coverage is 45.79%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #36496      +/-   ##
===========================================
+ Coverage    64.54%   64.61%   +0.06%     
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  Files          787      788       +1     
  Lines        61176    61428     +252     
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+ Hits         39486    39690     +204     
- Misses       21690    21738      +48     

Files Changed	Coverage Δ
...counts/report/accounts_payable/accounts_payable.py	100.00% <ø> (ø)
...counts_payable_summary/accounts_payable_summary.py	0.00% <ø> (ø)
..._receivable_summary/accounts_receivable_summary.py	0.00% <0.00%> (ø)
...counts/report/financial_ratios/financial_ratios.py	0.00% <0.00%> (ø)
erpnext/crm/doctype/lead/lead.py	68.03% <ø> (ø)
erpnext/accounts/party.py	77.40% <9.09%> (-0.76%)	⬇️
erpnext/accounts/doctype/account/account.py	73.18% <57.14%> (-0.42%)	⬇️
.../report/accounts_receivable/accounts_receivable.py	71.05% <60.00%> (-1.62%)	⬇️
erpnext/accounts/utils.py	73.85% <87.87%> (+0.41%)	⬆️
...xt/accounts/doctype/journal_entry/journal_entry.py	69.32% <90.90%> (+0.25%)	⬆️
... and 9 more

... and 3 files with indirect coverage changes