out_mongo: add MongoDB as default output plugin

[w4term3loon]

MongoDB output plugin as a default plugin to ease the process of setting up the connection between such databases and Fluent-bit.

I've opended an issue for the missing feature:

#8846

• Add MongoDB prerequisites to cmake build.
• Implement output plugin.
• Add cmake config options if needed.
• Add mongo-c-driver project to lib (may be unnecessary).
• Format code to match guidelines.

Addresses #8846

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Testing
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• Example configuration file for the change
• Debug log output from testing the change

• Attached Valgrind output that shows no leaks or memory corruption was found

If this is a change to the packaging of containers or native binaries then please confirm it works for all targets.

• [N/A] Run local packaging test showing all targets (including any new ones) build.
• [N/A] Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

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Backporting

• Backport to latest stable release.

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