Add stricter checks and normalisation of source code paths (Fixes SaaS-7700)

[senglezou]

Osv Scanner currently reports raw findings in the following example format:

          {
            "ruleId": "CVE-2025-22869",
            "ruleIndex": 0,
            "level": "warning",
            "message": {
              "text": .......')."
            },
            "locations": [
              {
                "physicalLocation": {
                  "artifactLocation": {
                    "uri": "file:///code/sample/go.mod"
                  }
                }
              }
            ]
          },

This the translate to the following log which is not ideal

{
        "activityId": "ACTIVITY_ID_CREATE",
        "activityName": "ACTIVITY_ID_CREATE",
        "categoryName": "CATEGORY_UID_FINDINGS",
        "categoryUid": "CATEGORY_UID_FINDINGS",
        "className": "CLASS_UID_VULNERABILITY_FINDING",
        "classUid": "CLASS_UID_VULNERABILITY_FINDING",
        "confidence": "CONFIDENCE_ID_UNKNOWN",
        "confidenceId": "CONFIDENCE_ID_UNKNOWN",
        "count": 1,
        "findingInfo": {
            "createdTime": "1757519922",
            "createdTimeDt": "2025-09-10T15:58:42.728397885Z",
            "dataSources": [
                "{\"targetType\":\"TARGET_TYPE_REPOSITORY\",\"uri\":{\"uriSchema\":\"URI_SCHEMA_FILE\",\"path\":\"file://file:///workspace/source-code/repo/go.sum\"},\"sourceCodeMetadata\":{\"repositoryUrl\":\"https://github.com/smithy-security/go-dvwa\"}}"
            ],
            "firstSeenTime": "1757519922",
            "firstSeenTimeDt": "2025-09-10T15:58:42.728397885Z",
            "lastSeenTime": "1757519922",
            "lastSeenTimeDt": "2025-09-10T15:58:42.728397885Z",
            "modifiedTime": "1757519922",
            "modifiedTimeDt": "2025-09-10T15:58:42.728397885Z",
            "productUid": "osv-scanner",
            "title": "CVE-2023-3978: Improper rendering of text nodes in golang.org/x/net/html",
            "uid": "CVE-2023-3978"
        },
        "metadata": {
            "eventCode": "CVE-2023-3978",
            "product": {
                "name": "osv-scanner"
            },
            "uid": "45a6439f-280d-5eff-9917-4790beb3084a"
        },
        "severity": "SEVERITY_ID_MEDIUM",
        "severityId": "SEVERITY_ID_MEDIUM",
        "startTime": "1757519922",
        "status": "STATUS_ID_NEW",
        "statusId": "STATUS_ID_NEW",
        "time": "1757519922",
        "timeDt": "2025-09-10T15:58:42.728397885Z",
        "typeName": "Create",
        "typeUid": "200201",
        "vulnerabilities": [
            {
                "affectedCode": [
                    {
                        "file": {
                            "name": "file:///workspace/source-code/repo/go.sum",
                            "path": "file://file:///workspace/source-code/repo/go.sum"
                        }
                    }
                ],
    },

The aim of this PR will be to fix this