Add pagination support to the `get_pull_request_files` tool.

### Describe the bug

Add pagination support to the `get_pull_request_files` tool.

### Affected version

v0.5.0

### Steps to reproduce the behavior

`get_pull_request_files` retrieves only the first 30 files with diffs of any PR that contains more than 30 files.

### Expected vs actual behavior

Support page and perPage parameters for the `get_pull_request_files` 

### Logs

N/A
