Improve Ruby Package Ecosystem/Datafile Handler to tag key_files properly

### Description

The Ruby Package Ecosystem miss to tag the `key_files` properly that affects the proper attributes population at Package Level and further the `license_clarity_score`
#### Example
While scanning https://github.com/inspec/inspec/archive/refs/tags/v6.8.2.zip , got the `license_clarity_score` as 0 with LICENSE at `inspec-bin/LICENSE` and not at root is not tagged as `key_file`

```json
{
"path": "inspec-6.8.2.tar.gz-extract/inspec-6.8.2/inspec-bin/LICENSE",
"type": "file",
"name": "LICENSE",
"base_name": "LICENSE",
"extension": "",
"size": 590,
"date": "2024-08-02",
"sha1": "f7fbb40d12aae4849b657cc27937e3a0f2b3dbad",
"md5": "81b0e16be045534c5330969d1e542bb4",
"sha256": "7f93f3fbf47c2b8129a7c1524f2fc9ed0b18e8cd0d21ab8f66dad6928ce43172",
"mime_type": "text/plain",
"file_type": "ASCII text",
"programming_language": null,
"is_binary": false,
"is_text": true,
"is_archive": false,
"is_media": false,
"is_source": false,
"is_script": false,
"package_data": [],
"for_packages": [],
"is_legal": true,
"is_manifest": false,
"is_readme": false,
"is_top_level": false,
"is_key_file": false,
"detected_license_expression": "apache-2.0",
"detected_license_expression_spdx": "Apache-2.0",
"license_detections": [
{
"license_expression": "apache-2.0",
"license_expression_spdx": "Apache-2.0",
"matches": [
{
"license_expression": "apache-2.0",
"spdx_license_expression": "Apache-2.0",
"from_file": "inspec-6.8.2.tar.gz-extract/inspec-6.8.2/inspec-bin/LICENSE",
"start_line": 3,
"end_line": 13,
"matcher": "2-aho",
"score": 100.0,
"matched_length": 85,
"match_coverage": 100.0,
"rule_relevance": 100,
"rule_identifier": "apache-2.0_7.RULE",
"rule_url": "https://github.com/nexB/scancode-toolkit/tree/develop/src/licensedcode/data/rules/apache-2.0_7.RULE",
"matched_text": " Licensed under the Apache License, Version 2.0 (the \"License\");\n you may not use this file except in compliance with the License.\n You may obtain a copy of the License at\n\n http://www.apache.org/licenses/LICENSE-2.0\n\n Unless required by applicable law or agreed to in writing, software\n distributed under the License is distributed on an \"AS IS\" BASIS,\n WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n See the License for the specific language governing permissions and\n limitations under the License.",
"matched_text_diagnostics": "Licensed under the Apache License, Version 2.0 (the \"License\");\n you may not use this file except in compliance with the License.\n You may obtain a copy of the License at\n\n http://www.apache.org/licenses/LICENSE-2.0\n\n Unless required by applicable law or agreed to in writing, software\n distributed under the License is distributed on an \"AS IS\" BASIS,\n WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n See the License for the specific language governing permissions and\n limitations under the License."
}
],
"detection_log": [],
"identifier": "apache_2_0-c4e30bcd-ccfd-bbc3-d2f1-196ab911e47d"
}
],
"license_clues": [],
"percentage_of_license_text": 93.41,
"copyrights": [
{
"copyright": "Copyright (c) 2019 Chef Software Inc.",
"start_line": 1,
"end_line": 1
}
],
"holders": [
{
"holder": "Chef Software Inc.",
"start_line": 1,
"end_line": 1
}
],
"authors": [],
"emails": [],
"urls": [
{
"url": "http://www.apache.org/licenses/LICENSE-2.0",
"start_line": 7,
"end_line": 7
}
],
"files_count": 0,
"dirs_count": 0,
"size_count": 0,
"scan_errors": []
},
{
```

https://rubygems.org/gems/inspec-bin

Consequently the package attributes like copyright, holder, etc are not populated well and got the `license_clarity_score` as 0