RFR: JDK-8309150: Need to escape " inside attribute values [v2]

[Jonathan Gibbons]

> Please review a trivial PR to escape `"` as `"` when writing HTML attribute values enclosed in `"`.
> 
> A simple test is added, using a `@spec` tag to introduce a user-defined `id`.
> 
> The inverse transformation (from `"` to `"`) needs to be done in the `HtmlParser` for the `JavadocTester` framework.

Jonathan Gibbons has updated the pull request incrementally with one additional commit since the last revision:

  update copyright years

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14234/files
  - new: https://git.openjdk.org/jdk/pull/14234/files/aa0cb83a..2e06c0f2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14234&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14234&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/14234.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14234/head:pull/14234

PR: https://git.openjdk.org/jdk/pull/14234