feat: add --preview flag to preview aviator remediations before applying

[dhanwanthp]

This MR adds a new --preview flag to the fcli aviator ssc apply-remediations and fcli fod aviator apply-remediations commands, enabling users to preview what changes would be applied to their source code without actually modifying files.

Features:

• Added --preview option to both SSC and FoD apply-remediations commands
• When enabled, the tool performs full validation and processing without modifying source files
• Returns detailed JSON output containing:
  • All proposed code changes per issue ID
  • File paths and encodings
  • Line numbers and code snippets (before/after)
  • Context metadata for fuzzy matching
  • Skip reasons for any failed remediations

Usage:

# Preview changes without applying them
fcli aviator ssc apply-remediations --appversion myapp --preview

# Preview specific issues only
fcli aviator ssc apply-remediations --appversion myapp --preview --issue-ids ISSUE-123,ISSUE-456

# Apply changes (existing behavior, no --preview flag)
fcli aviator ssc apply-remediations --appversion myapp

Output format:-

{
  "previewMode": true,
  "totalRemediation": 10,
  "appliedRemediation": 8,
  "previewDetails": [
    {
      "issueId": "ISSUE-123",
      "status": "available",
      "files": {
        "src/Example.java": {
          "filename": "src/Example.java",
          "path": "src/Example.java",
          "encoding": "UTF-8",
          "changes": [
            {
              "changeIndex": 1,
              "lineFrom": 42,
              "lineTo": 44,
              "originalCode": "...",
              "newCode": "...",
              "context": { "linesBefore": 2, "linesAfter": 2, "content": "..." },
              "fuzzyMatched": false
            }
          ]
        }
      }
    }
  ]
}