RFR: 8286654: Add an optional description accessor on ToolProvider interface

[Christian Stein]

This PR adds an optional description accessor on `ToolProvider` interface.

This PR also adds short description for each of the listed tool:
- `jar`
- `javac`
- `javadoc`
- `javap` and `jdeps`
- `jlink` and `jmod`
- `jpackage`

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Commit messages:
 - Add localized description for `jpackage`
 - Add localized description for `jlink` and `jmod`
 - Add localized description for `javap` and `jdeps`
 - Add localized description for `javadoc`
 - Add localized description for `jar`
 - Add localized description for `javac`
 - 8286654: Add an optional description accessor on ToolProvider interface

Changes: https://git.openjdk.java.net/jdk/pull/8772/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8772&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286654
  Stats: 115 lines in 19 files changed: 97 ins; 2 del; 16 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8772.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8772/head:pull/8772

PR: https://git.openjdk.java.net/jdk/pull/8772