use correct debit and credit values, handle journal entries with multiple legs and docs

[dvdl16]

Description

• fix: use correct debit and credit values
• feat: handle journal entries with multiple legs
• chore: standardise docs to vuepress

Type of change

• ⚪ Bug fix (change which fixes an issue)
• 🟢 New feature (change which adds functionality)
• ⚪ Breaking change (fix or feature that would cause existing functionality to not work as expected)

Tests

• Unit Tests have been updated or added, as required
• UI Tests have been updated or added, as required

Checklist:

• My code follows Naming Guidelines (DocType, Field and Variable naming)
• No Form changes / My code follows the Form Design Guidelines
• My code follows the Coding Standards of this project
• My code follows the Code Security Guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas / No comments necessary
• I have made corresponding additions/changes to the documentation
• All business logic and validations are on the server-side / No business logic or validation changes
• No patches are necessary / Migration Patches have been added to the correct subdirectory of /patches and patches.txt have been updated

User Experience:

N/A

[codecov-commenter]

Codecov Report

❌ Patch coverage is 51.72414% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 39.14%. Comparing base (79c029f) to head (41f7c57).

Files with missing lines	Patch %	Lines
...e/value_added_tax_return/value_added_tax_return.py	51.85%	13 Missing ⚠️
csf_za/__init__.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff               @@
##           version-15      #36      +/-   ##
==============================================
- Coverage       40.16%   39.14%   -1.03%     
==============================================
  Files              10        9       -1     
  Lines             473      442      -31     
==============================================
- Hits              190      173      -17     
+ Misses            283      269      -14     

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[Starktail-Christo]

@dvdl16 What changes were made on this PR?

[dvdl16]

@dvdl16 What changes were made on this PR?

@Starktail-Christo

• fix: use correct debit and credit values

For invoices in foreign currencies, use the ZAR value, not the foreign currency value

• feat: handle journal entries with multiple legs

Before this PR, auto-classification only worked for simple journal entries with VAT, e.g.

Bought office supplies for 100 + 15 VAT, paid from bank.
Total paid = 115.

| Account                     | Debit | Credit |
|-----------------------------|-------|--------|
| Office Supplies (Expense)   | 100   |        |
| VAT                         | 15    |        |
| Bank                        |       | 115    |

The added code handles more scenarios of messy/real-world journal entries where VAT appears as one line, but the other side is split across multiple lines

[dvdl16]

@Starktail-Christo was part of work done for HD Ticket 854

[Starktail-Christo]

@dvdl16 Thank you for the clarification