Avoid the intermediate array allocation in project OtherOptions

[xperiandri]

Description

Split out of #20274 at T-Gro's request — the original rewrite there also silently reversed the -r: flag order, which this version does not.

FSharpProjectOptionsReactor.tryComputeOptionsBySingleScriptOrFile built the OtherOptions array for an F#-metadata project as:

project.ProjectReferences
|> Seq.map (fun x -> "-r:" + project.Solution.GetProject(x.ProjectId).OutputFilePath)
|> Array.ofSeq
|> Array.append (
    project.MetadataReferences.OfType<PortableExecutableReference>()
    |> Seq.map (fun x -> "-r:" + x.FilePath)
    |> Array.ofSeq
)

Two arrays are allocated (Array.ofSeq twice) and a third for the concatenation (Array.append). Replaced with a single array comprehension that yields both reference kinds directly, preserving the original element order (metadata references, then project references) so no consumer-visible behavior changes.

This runs once per non-open-document, non-script F# file whose project is compiled from a project-system snapshot, so the allocation count scales with reference count × such computations.

Checklist

• Test cases added — mechanical allocation-only refactor, no behavior change to cover.
• Performance benchmarks added in case of performance changes — not applicable; this is a straightforward allocation-count reduction (3 arrays → 1), not a hot-path change requiring a BDN benchmark.
• Release notes entry updated: docs/release-notes/.VisualStudio/18.vNext.md (added in a follow-up commit once this PR's number was known).

🤖 Generated with Claude Code

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✅ Found changes and release notes in following paths:

Change path	Release notes path	Description
`vsintegration/src`	docs/release-notes/.VisualStudio/18.vNext.md

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🔍 Tooling Safety Check — Affects-Design-Time
Affects-Design-Time: Modifies IDE project-options code that runs during design time.

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