scylla-cql: Avoid index-access to buffer

[Lorak-mmk]

If buffer is too short and we index past its end, code will panic. This is not desirable - we want to return errors on invalid protocol messages.

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• I added relevant tests for new features and bug fixes.
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• PR description sums up the changes and reasons why they should be introduced.
• I have provided docstrings for the public items that I want to introduce.
• I have adjusted the documentation in ./docs/source/.
• I added appropriate Fixes: annotations to PR description.

[Copilot]

Pull Request Overview

This PR refactors deserialization code to use existing helper functions instead of manual buffer manipulation. The changes replace direct buffer slicing and advancement operations with calls to read_raw_bytes() and read_short_bytes(), improving code consistency and reducing duplication.

Key changes:

• Replace manual buffer slicing with read_raw_bytes() helper in IP address deserialization
• Replace manual length reading and slicing with read_short_bytes() in prepared statement ID parsing
• Remove unused Buf trait imports from both modified files

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
scylla-cql/src/frame/types.rs	Refactored read_inet() to use read_raw_bytes() helper; removed unused Buf import
scylla-cql/src/frame/response/result.rs	Refactored deser_prepared() to use read_short_bytes() helper; removed unused Buf import
scylla-cql/src/frame/frame_errors.rs	Added IdParseError variant to support the refactored error handling

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[github-actions]

cargo semver-checks found no API-breaking changes in this PR.
Checked commit: 900a980