[.github] Create reusable action get-issue-number

[mikeharder]

https://github.com/Azure/azure-rest-api-specs/pull/36405/files#r2248994009

      - name: "Get Issue Number"
        id: get-issue-number
        uses: actions/github-script@v7
        with:
          script: |
            const { extractInputs } =
              await import('${{ github.workspace }}/.github/workflows/src/context.js');
            const { issue_number } = await extractInputs({ github, context, core });
            core.setOutput("issue_number", issue_number);

Also create reusable action add-issue-number-artifact