Cleanup VectorSet TODOs

[tiagonapoli]

RESP parsing

• Cap maximum RESP array element count at 1M
• Add bounds validation in GetSerializedRecordSpan for cluster migration payloads

VectorSet commands

• Validate vector dimensions, EF, M, COUNT, FILTER-EF, and REDUCE at parse time
• Cap MaxRetrieveCount at 100M to prevent excessive allocations in VSIM
• Fix incorrect buffer size comparison and add overflow check in VectorManager.VectorSimilarity distances buffer
• Reduce stackalloc size in TryGetEmbedding to a fixed 1KB instead of worst case 64kb

[Copilot]

Pull request overview

This PR tightens validation and error-handling around RESP parsing and VectorSet commands, and adds regression tests to ensure oversized inputs are rejected safely (without overflow or excessive allocations).

Changes:

• Add a maximum RESP array argument-count guard and a dedicated parsing exception for excessive argument counts.
• Harden vector command parsing/validation (dimension limits, EF/COUNT/FILTER-EF bounds) and refactor VSIM output buffer sizing helpers.
• Add/adjust tests for the new guards and validation behavior (RESP parsing, RespReadUtils serialized span parsing, VectorSet error cases).

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
test/standalone/Garnet.test/RespTests.cs	Adds an end-to-end socket test to ensure excessive RESP array argument counts are rejected and the session is closed.
test/standalone/Garnet.test/Resp/RespReadUtilsTests.cs	Adds unit tests covering valid/invalid length-prefixed record parsing for GetSerializedRecordSpan.
test/standalone/Garnet.test.vectorset/RespVectorSetTests.cs	Updates VectorSet error-message expectations and adds new validation/error-path tests for VADD/VSIM.
libs/server/Resp/Vector/VectorManager.cs	Introduces shared limits (dimensions/EF/retrieve count) and refactors VSIM buffer sizing into helpers.
libs/server/Resp/Vector/RespServerSessionVectors.cs	Enforces new VectorSet parameter bounds (dims/EF/COUNT/FILTER-EF) and improves related error messages.
libs/server/Resp/Parser/RespCommand.cs	Adds MaxRespArrayLength and throws a parsing exception when the argument count exceeds the limit.
libs/common/RespReadUtils.cs	Adds bounds validation for serialized-record spans based on the length prefix.
libs/common/Parsing/RespParsingException.cs	Adds ThrowExcessiveArgumentCount to standardize the new protocol error.