feat(xero): Add MCP Sever for Xero

[udaykakade25]

Description

Adds MCP Server for Xero.

Related issue

No.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New MCP feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Other (please specify)

How has this been tested?

(Add screenshots or recordings here if applicable.)
Tested using Claude and verified on Xero Developers website.

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing tests pass locally with my changes

[udaykakade25]

Hey @zihaolin96 !
Here are some screenshots of tools: https://drive.google.com/drive/folders/1xou7KFAfg2s8UObtSvzlGA_Is4G8uob6?usp=sharing
All the tool files are working fine!