Content mapper duplicated inlay hints

@andrewbranch 已经在做这个了。

开始于 2026年8月27日。

### 🔎 Search Terms

inlay hints
content-mapper

### 🕗 Version & Regression Information

I was unable to test this on prior versions because this is newly added

### ⏯ Playground Link

_No response_

### 💻 Code

### 🙁 Actual behavior

When a content mapper splits a statement into multiple spans, the inlay hints result is duplicated. In the inlay hints request, the request range is mapped into multiple ranges and calculated separately. Because the statement is in multiple spans, the hint for that statement is returned multiple times.

Four slash test failed case:
```go
package fourslash_test

import (
"testing"

"github.com/microsoft/TypeScript/tsc/internal/ls/lsutil"
"github.com/microsoft/TypeScript/tsc/internal/testutil"
"github.com/microsoft/TypeScript/tsc/internal/testutil/contentmappertest"
)

func TestContentMapperInlayHints(t *testing.T) {
t.Parallel()
defer testutil.RecoverAndFail(t, "Panic on fourslash test")
f, done := newContentMapperFourslash(t, `// @Filename: /app.lisp
(+ 1 2 "oops")

// @Filename: /main.ts
declare function add(a: number, b: number, c: string): number;
`, contentmappertest.LispMapper, ".lisp")
defer done()

f.GoToFile(t, "/app.lisp")
f.VerifyBaselineInlayHints(t, nil /*span*/, &lsutil.UserPreferences{InlayHints: lsutil.InlayHintsPreferences{IncludeInlayParameterNameHints: lsutil.IncludeInlayParameterNameHintsAll}})
}
```

### 🙂 Expected behavior

Probably need to deduplicate when multiple spans map to the inlay hint request range.

### Additional information about the issue

_No response_