[modem]: Build job with cmake v2

[david-cermak]

followup on #1039

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Note

Medium Risk
Moderate risk because it changes build-system integration for esp_modem and adds a new CI build path; failures could block builds across IDF v6/v2 configurations.

Overview
Adds a new CI job to build esp_modem’s ap_to_pppos example using ESP-IDF’s CMake build system v2 (IDF release-v6.0), generating a minimal top-level CMakeLists.txt and using EXTRA_COMPONENT_DIRS to avoid component manager override issues.

Updates components/esp_modem to detect IDF_BUILD_V2 and switch to a new CMakeLists_v2.txt that builds the component via add_library, wires include dirs/link deps, enforces C++17, and safely links idf::main only when present (for CONFIG_ESP_MODEM_ADD_CUSTOM_MODULE). Also tightens the ap_to_pppos example’s main component to explicitly REQUIRES its runtime dependencies.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Unused optional_deps variable declared but never referenced

Low Severity

The optional_deps list is initialized on line 5 but is never populated or referenced anywhere in CMakeLists_v2.txt (or anywhere else in the codebase). Only public_deps is actually used. This appears to be leftover scaffolding — possibly intended for the optional main dependency handling at the bottom of the file, which ended up using a different approach (generator expression with TARGET_EXISTS).

 

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