RFR: 8345908: Class links should be properly spaced

[Hannes Wallnöfer]

Please review a trivial change to apply monospace font not just to the class links at the top of class and interface pages, but also to the comma and space characters between them. The comma-space separators currently use proportional font, which results in very narrow spacing that does not match the class name font.

Using the same monospace font for everything makes individual class names more discernible, and makes it easier to pick out individual class names. This is especially true for multiline class lists such as the subinterfaces of `java.lang.Autoclosable` below.

Before:

<img width="862" alt="class-links-old" src="https://github.com/user-attachments/assets/ea9679fa-8b41-46ea-9ad1-1f31bdfc6bce">

After:

<img width="869" alt="class-links-new" src="https://github.com/user-attachments/assets/9d712d1a-5f83-4b49-971e-b06f2f4d1a0c">

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Commit messages:
 - 8345908: Class links should be properly spaced

Changes: https://git.openjdk.org/jdk/pull/22662/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22662&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345908
  Stats: 27 lines in 6 files changed: 0 ins; 3 del; 24 mod
  Patch: https://git.openjdk.org/jdk/pull/22662.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22662/head:pull/22662

PR: https://git.openjdk.org/jdk/pull/22662