feat: add inja example

[vansangpfiev]

Describe Your Changes

This pull request introduces a new example project for the inja template engine within the engine/examples directory. The changes include updates to the CMake configuration to support this new example, the addition of new source files, and a sample data file.

CMake Configuration Updates:

• engine/CMakeLists.txt: Added an option to enable the inja example and conditionally include the examples/inja directory.
• engine/examples/inja/CMakeLists.txt: Created a new CMake configuration file for the inja example, setting the C++ standard based on available features and configuring necessary libraries.

New Example Files:

• engine/examples/inja/main.cc: Added the main source file for the inja example, which includes command-line argument parsing and template rendering logic.
• engine/examples/inja/template.txt: Added a sample template file for the inja example.
• engine/examples/inja/data.txt: Added a sample data file for the inja example.

Fixes Issues

• idea: support tool to test transform template for remote engines #1967

Self Checklist

• Added relevant comments, esp in complex areas
• Updated docs (for bug fixes / features)
• Created issues for follow-up changes or refactoring needed