Preserve inline `ghc-options` formatting from existing `.cabal` file

**Problem:**  
`hpack` merges multiple `ghc-options` entries into a single line or changes indentation. Related: #617

**Expected behavior:**  
Keep each `ghc-options` entry on its own line with the original indentation.

**Example:**

-- Before (Gild-formatted)

```cabal
ghc-options:
  -Wall
  -Wcompat
  -Widentities
```
-- After (hpack)

```cabal
ghc-options: -Wall -Wcompat -Widentities
```
