feat: add opentelemetry-resource-detector crate

[rogercoll]

Moves the implementation of the OS and Process resource detectors from the opentelemetry-sdk to its own contrib crate. The reason behind it is due to their experimental nature in semantic conventions:

• OS: https://github.com/open-telemetry/opentelemetry-specification/blob/v1.6.x/specification/resource/semantic_conventions/os.md
• Process: https://github.com/open-telemetry/opentelemetry-specification/blob/v1.6.x/specification/resource/semantic_conventions/process.md

Discussion: https://github.com/open-telemetry/opentelemetry-rust/pull/1610

Changes

Adds a new crate for contrib resource detectors.

Merge requirement checklist

• [x] CONTRIBUTING guidelines followed
• [x] Unit tests added/updated (if applicable)
• [x] Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• [x] Changes in public API reviewed (if applicable)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 50.5%. Comparing base (93dc0d9) to head (9805203).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #49 +/- ## ======================================= + Coverage 50.1% 50.5% +0.4% ======================================= Files 32 34 +2 Lines 4358 4397 +39 ======================================= + Hits 2184 2223 +39 Misses 2174 2174 ```

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