[16.0][ADD] project_purchase_budget: add new module

[marcelsavegnago]

This pull request introduces a new Odoo module, project_purchase_budget, which enforces purchase budget controls at the project level. The module allows project managers to set a maximum percentage of the sale value that can be spent on purchases for a project. When purchase orders exceed this budget, a tier validation process is triggered. The implementation includes models, security rules, tier validation definitions, and comprehensive documentation.

The most important changes are:

Core Functionality Implementation:

• Added the main module manifest (__manifest__.py) declaring dependencies, data files, and metadata for project_purchase_budget.
• Implemented the ProjectProject model extension in project_project.py to track and compute purchase budget KPIs (budget, spent, remaining, consumed %, and contribution), and to determine if the current user is a purchase budget manager.
• Extended the PurchaseOrder model in purchase_order.py to compute if a purchase order exceeds any linked project's budget, trigger tier validation, and ensure correct recalculation and invalidation of related KPIs.

Tier Validation and Security:

• Added a tier validation rule in tier_definition_data.xml to require approval when a purchase order exceeds the project budget, and defined the necessary security group.

Documentation:

• Added a comprehensive README.rst and additional documentation files (INSTALL.rst, CONFIGURE.rst, USAGE.rst, DESCRIPTION.rst, CONTRIBUTORS.rst) describing the module's purpose, installation, configuration, usage, and credits. [1] [2] [3] [4] [5] [6]

These changes collectively provide a robust framework for project purchase budget management with validation and clear user guidance.

[codecov]

Codecov Report

❌ Patch coverage is 99.35691% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.63%. Comparing base (e6370f8) to head (8ed20ba).

Files with missing lines	Patch %	Lines
project_purchase_budget/models/project_project.py	98.80%	0 Missing and 1 partial ⚠️
...chase_budget/tests/test_project_purchase_budget.py	99.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             16.0      #24      +/-   ##
==========================================
+ Coverage   92.85%   97.63%   +4.77%     
==========================================
  Files           9       15       +6     
  Lines         112      423     +311     
  Branches        6       31      +25     
==========================================
+ Hits          104      413     +309     
  Misses          5        5              
- Partials        3        5       +2     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.