RFR: 8332103: Add missing `@since` tags to `java.desktop`

[Nizar Benalla]

If you're currently reviewing this PR, thank you!
Most fixes here are according to the reports by the since checker tool in #18934 and are pretty simple.

To make reviewing easier
- `BasicSliderUI` has the constructor `public BasicSliderUI(JSlider b)` for a long time so the default constructor (without parameters) didn't exist until JDK 16

For the `package-info` files, it is pretty hard to find source code of JDK 1-5 so I used the `grep` command to find the oldest instance of an `@since` in those packages.

I found instances of `@since 1.1` in the other packages but `javax/swing/plaf/synth/package-info.java` might be worth checking as most classes there had no `@since`.

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Commit messages:
 - Add `@since` tags to `java.desktop`

Changes: https://git.openjdk.org/jdk/pull/19192/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19192&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8332103
  Stats: 42 lines in 9 files changed: 34 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/19192.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19192/head:pull/19192

PR: https://git.openjdk.org/jdk/pull/19192