Fix up hover code, mostly temporary

[jakebailey]

The writing and clearing and passing down of things doesn't seem to be working; for now just flip this all to use the returned string until we can do something faster. (I'm not doing something faster because some of the code does some truncation that is not easily doable via streaming.)

Also the unknown symbol flip.

[Copilot]

Pull Request Overview

The PR refactors hover text generation to use direct string builders and streamlines printer utilities for single-line output, while temporarily bypassing streaming truncation logic and flipping the unknown-symbol check.

• Introduces GetSingleLineStringWriter and makes the pool private for more controlled writer reuse.
• Replaces EmitTextWriter usage in ProvideHover with strings.Builder and inverts the unknown-symbol condition.
• Removes explicit writer parameters from typeToStringEx/symbolToStringEx and related methods, centralizing them via the new pool API.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
internal/printer/singlelinestringwriter.go	Renamed pool var to private and added GetSingleLineStringWriter/release function.
internal/ls/hover.go	Switched hover formatting to strings.Builder, removed printer dependency, flipped unknown-symbol logic.
internal/checker/symbolaccessibility.go	Updated calls to symbolToStringEx to match new signature (dropped writer arg).
internal/checker/relater.go	Removed writer arg in error-reporting calls to typeToStringEx.
internal/checker/printer.go	Simplified internal typeToStringEx, symbolToStringEx, etc., to use the new pool API and drop writer args.
internal/checker/checker.go	Updated calls to typeToStringEx in diagnostic methods to match new signature.

Comments suppressed due to low confidence (2)

internal/ls/hover.go:20

• [nitpick] The parameter name b is ambiguous; consider renaming it to builder for clarity.

func writeTypeParam(c *checker.Checker, tp *checker.Type, file *ast.SourceFile, b *strings.Builder) {

internal/ls/hover.go:20

• strings.Builder is used in this file but the "strings" package is not imported; add import "strings" to the import block.

func writeTypeParam(c *checker.Checker, tp *checker.Type, file *ast.SourceFile, b *strings.Builder) {

[jakebailey]

Last commit optional, that's mainly there per request (presumably to make the markdown easier)

[ahejlsberg]

Otherwise, looks good to me.