feat: Improve jf scan summary for unsupported file types

[davidkopiel]

Currently, when jf scan is run on a file whose type is not supported by the Xray indexer (e.g., a plain .txt or .exe file), the command completes successfully but prints the summary message: ✨ No vulnerable components were found ✨. This is misleading for users, as it implies the file was scanned and found clean, rather than indicating it wasn't scanned at all due to incompatibility.

Solution:

This PR implements the following changes to provide clearer feedback in this scenario:

Added Warning: A log.Warn message is now printed immediately when the indexer skips a file due to an unsupported type (exit code 3), explicitly informing the user about that specific file. (Change in commands/scan/scan.go)
Track Scannable State: A new boolean field HasScannableComponents was added to the results.SecurityCommandResults struct to track whether at least one file in the scan input was successfully indexed and processed (i.e., was of a supported type). (Change in utils/results/results.go)
Set Tracking Flag: Logic was added at the end of the RunScan function to set the HasScannableComponents flag based on whether any TargetResults had their Technology identified. (Change in commands/scan/scan.go)
Conditional Summary: The output logic (in utils/results/output/resultwriter.go) was modified. Before printing the final summary, it now checks:
If zero vulnerabilities were found AND the HasScannableComponents flag is false AND files were actually attempted, it prints a new, more accurate summary: ✨ Scan completed: No files of a supported type were found or scanned. ✨
Otherwise, it prints the original summary ("No vulnerable components found" or the vulnerability table).
Benefit:

This change significantly improves the user experience by:

Providing immediate feedback when a file is skipped due to its type.
Displaying a clear and accurate summary message when only unsupported files are scanned, preventing confusion.
Testing:

Verified locally by running the modified jf scan command against:

An unsupported file type (e.g., .txt, .exe): Confirmed the warning and the new summary message appear.
A supported file type with no vulnerabilities: Confirmed the standard "No vulnerable components" message appears.
A supported file type with vulnerabilities: Confirmed the vulnerability table appears correctly.

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[davidkopiel]

I have read the CLA Document and I hereby sign the CLA