feat(C/C++): add C/C++ namespace SDK

[aheev]

• stable C-ABI, C++ RAII wrappers
• structure similar to python. impls live in lance-c
• use openapi-generator-cli::opencpp-restsdk for rest-client generation and add a C shim layer in the core

[github-actions]

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[aheev]

@wjones127 @jackye1995

I need input on rest-client integration into core

The current approach to integrating rest-client into the core and re-exposing models and apis is not working very well. Right now I am generating rest-client C++ lib using openapi-generator::cpp-restsdk and then adding a C shim layer(> 100 model and api classes rewritten in C)

When I asked Claude, it suggested the following approaches

• Generate C/C++ REST client using patched C/C++ templates in one go

C generator is notorious for poorly maintained and generating code that's hard to integrate (When I pointed Claude at a generated model, it found out memory leaks and data type issues)

So, use C/C++ patched templates with `openapi-generator`: fixing issues in generated C client + RAII wrappers for C++
 

• Generate C and C++ rest clients separately

Use patched template for C rest client and `cpp-restsdk` for C++ rest client

What do you think? Feel free to suggest any alternative approaches as well

CC: @jja725