Added legacy issue template

Added legacy issue template

This PR is to support compatibility of issue template between different github versions.

**Changes proposed in this PR:**
1. Added legacy issue template

**Reference:**
* Legacy issue template: ./.github/ISSUE_TEMPLATE.md
* Up-to-date issue template: ./.github/ISSUE_TEMPLATE/{Bug_report.md|Feature_request.md|Support_request.md}

* Our request for github.sec.samsung.neet:
   * https://github.sec.samsung.net/SERVICE/GitHub/issues/124

**Self assessment:**
1. GBS build: okay
2. Local test: okay

Signed-off-by: Geunsik Lim <geunsik.lim@samsung.com>