RFR: 8180066: Convert package.html files to package-info.java

[Kevin Rushforth]

This is a doc cleanup task to convert all `package.html` files to `package-info.java`, which is the recommended way to provide package documentation.

The first commit is the result of running a shell script that @jonathan-gibbons provided. The second commit removes an errant `<h2>` tag from the `package-info.java` for one package, `javafx.util.converter` that is unneeded and unwanted. That same file also had a redundant first sentence, which was coincidentally removed by the tool, so once I removed the `<h2>` tag the docs for that package now looks good and matches the other packages. There are no other changes in the javadoc-generated API docs.

One thing I didn't do is add a ` *` at the beginning of the lines that are now part of a javadoc-style comment block. This minimizes the diffs, but it means we won't be using the usual pattern for those comment blocks. I'm inclined to file a follow-up issue rather than changing that now.

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Commit messages:
 - Fix whitespace
 - Remove erroneous <h2> tag
 - 8180066: Convert package.html files to package-info.java

Changes: https://git.openjdk.org/jfx/pull/1159/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1159&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8180066
  Stats: 2982 lines in 68 files changed: 1289 ins; 1649 del; 44 mod
  Patch: https://git.openjdk.org/jfx/pull/1159.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1159/head:pull/1159

PR: https://git.openjdk.org/jfx/pull/1159