Build C++ SDK on Linux with existing thirdparty packages.

**Query/Question**
Is is possible to build the C++ SDK using cmake but without using vcpkg?

***Why is this not a Bug or a feature Request?***
We already have certain packages installed that the SDK uses. Like libabsl.

When I the SDK build, it somehow determines to download all packages and build those versions. I'd like to somehow say to use the versions I already have on the system.

**Setup (please complete the following information if applicable):**
- OS: [e.g. iOS]
- IDE : [e.g. IntelliJ]
- Version of the Library used

**Information Checklist**
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- [ ] Query Added
- [ ] Setup information Added