RFR: 8352982: gradle TEST_SDK_PATH param doesn't work with relative paths [v3]

[Ambarish Rapte]

> Issue:
> The test execution fails when a relative path is specified a relative path for `TEST_SDK_PATH`.
> For example:
> 1. gradle -PTEST_ONLY=true -PTEST_SDK_PATH=**..**/jfx1/build test 
> 2. gradle -PTEST_ONLY=true -PTEST_SDK_PATH=**~**/jfx1/build test
> 
> Solution:
> Convert the relative path to an absolute path.
> 
> More about fix:
> The property TEST_SDK_PATH belongs to the root project rt in build.gradle.
> If we modify this property in build.gradle, it does not reflect in the child projects. The child projects for example graphics, controls would still have the value of TEST_SDK_PATH before modification.
> To solve this, I Introduced a new variable in build.gradle `TEST_SDK_DIR`. It would hold the modified value of `TEST_SDK_PATH` and gets correctly reflected across all sub-projects.
> 
> Verified that both relative paths and absolute path work fine after this change.

Ambarish Rapte has updated the pull request incrementally with one additional commit since the last revision:

  review fix

-------------

Changes:
  - all: https://git.openjdk.org/jfx/pull/1751/files
  - new: https://git.openjdk.org/jfx/pull/1751/files/92945555..021d9069

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1751&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1751&range=01-02

  Stats: 9 lines in 1 file changed: 3 ins; 5 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1751.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1751/head:pull/1751

PR: https://git.openjdk.org/jfx/pull/1751