fix: paid_amount when the group is mode of payment

[HarryPaulo]

OBS: R$ is a currency

Problem: If i create a invoice with total amount of R$ 100, paying this with two mode of payments:
Cash / Money: R$ 80
Credit Card: R$ 20

Using the report POS Register, set the filter "group_by" based on payment method, column Paid Amount show R$ 100 for both mode of payments, this is wrong.

>> Now With the fix <<

Now whent we group based on payment method, the amount will be based on mode of payment Cash / Money: R$ 80 and Credit Card: R$ 20

If we have change, this amount will be discounted on CASH type.

Example 1: one sale with amount R$ 90.

Example 2:
This situation is not common, and is not allowed in many establishments, but it is the following, R$ 100 was sold, with payment of R$ 120 on the credit card, generating a change of R$ 20, the change will be made and deducted from the cash payment method.

As the amount came out of the drawer to give change, in this case it will be negative, deducting from the general balance of the payment in "Cash / Money"

[codecov]

Codecov Report

Merging #36092 (2268f7d) into develop (7fb1e5b) will increase coverage by 0.48%.
The diff coverage is 0.00%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #36092      +/-   ##
===========================================
+ Coverage    63.72%   64.20%   +0.48%     
===========================================
  Files          813      785      -28     
  Lines        60113    60704     +591     
===========================================
+ Hits         38307    38975     +668     
+ Misses       21806    21729      -77     

Impacted Files	Coverage Δ
...pnext/accounts/report/pos_register/pos_register.py	0.00% <0.00%> (ø)

... and 172 files with indirect coverage changes

[stale]

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[HarryPaulo]

waiting for reviewers