Renaming Issue Templates correctly and adding a pull request template

Signed-off-by: tariqibrahim <tariq.ibrahim@microsoft.com>

.github/PULL_REQUEST_TEMPLATE.md

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+**What this PR does / why we need it**:
+
+**Special notes for your reviewer**:
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+**If applicable**:
+- [ ] this PR contains documentation
+- [ ] this PR contains unit tests
+- [ ] this PR has been tested for backwards compatibility