- introuce capability of accessing and referencing custom placeholders of PRs in the global template
```
${{CUSTOM_PLACEHOLDER[0]}}
${{CUSTOM_PLACEHOLDER[*]}}
```
- introduce new testcase checking the custom placeholder functionality
- introuce capability of accessing and referencing custom placeholders of PRs in the global template
```
${{CUSTOM_PLACEHOLDER[0]}}
${{CUSTOM_PLACEHOLDER[*]}}
```
- introduce new testcase checking the custom placeholder functionality