RFR: 8258240: make vscode-project on Windows generates jdk.code-workspace file with unescaped '\' in paths

[Daniel Jelinski]

Backslashes in `sed` replacement string are interpreted by `sed`. In order to output the strings we want, the replacement text needs to be escaped again. See https://stackoverflow.com/a/2705678

Verified that with this patch VSCode is able to open the workspace, and all files are visible in "Explorer".

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Commit messages:
 - Escape SED replacement string

Changes: https://git.openjdk.java.net/jdk/pull/7083/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7083&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258240
  Stats: 15 lines in 1 file changed: 7 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7083.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7083/head:pull/7083

PR: https://git.openjdk.java.net/jdk/pull/7083