RFR: JDK-8324774: Add DejaVu web fonts

[Hannes Wallnöfer]

This change adds the DejaVu web fonts that were previously maintained externally to the open repository so they are available both in JDK API documentation and any API documentation generated with the `javadoc` tool. All files added in this PR are the same as the ones previously maintained externally, with the exception of added license and name/version comments in `dejavu.css`.

Copying of font files to the generated documentation is done by looking for font file names in `dejavu.css`, so font file names can be changed without changing the code. However, the font file list is hard-coded in `APITest.java`. `CheckLibraryVersions.java` is updated to make sure the name and version in the legal file matches the one in the stylesheet. Of course I also performed manual tests to make sure the font and legal files are copied to the output tree and used correctly in browsers.

Once #17411 is integrated, `dejavu.css` should also be added to the list of files checked by the new "pass-through" test.

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Commit messages:
 - Add license comment
 - JDK-8324774: Add DejaVu web fonts

Changes: https://git.openjdk.org/jdk/pull/17633/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17633&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8324774
  Stats: 373 lines in 32 files changed: 361 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/17633.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17633/head:pull/17633

PR: https://git.openjdk.org/jdk/pull/17633