imgtool: Output format option to dumpinfo

[5frank]

Add -f, --format option to support multiple output formats (human, yaml,
json). Default yaml for file, default human for stdout - backward
compatible.

Details:

• Human output is unchanged
• Refactored dump_imginfo() to separate data reading from formatting
• JSON output uses hex strings for binary data (e.g., "e3a333ca...")
• YAML and JSON have both "type" (int) and "type_name" (str) for TLVs
• Image filename (basename) is included in all output formats
• Argument --silent is silently ignored. Doesn't make sense for a
  command that outputs data. i.e. No output on success. This is the same
  as for other sub commands

[nordicjm]

@fundakol please review

[nordicjm]

@5frank please see failing CI

[fundakol]

Usage of dumpinfo is now very confusing.

• this command does nothing: imgtool dumpinfo zephyr.signed.bin --format human -o dump.txt --silent
• this command: imgtool dumpinfo zephyr.signed.bin --format human -o dump.txt works same as imgtool dumpinfo zephyr.signed.bin and imgtool dumpinfo zephyr.signed.bin --format yaml
• when human format is selected option outfile has no effect

imgtool dumpinfo zephyr.signed.bin --format yaml -o dump.yaml --> produced different yaml then it was before your change, so it is not backward compatible.

[5frank]

@fundakol Tanks for the feedback!
You are right, it is confusing. --silent option makes no sense in combination with dumpinfo. Perhaps it had some purpose before!? I changed it to be silently ignored.

[5frank]

Sorry for fragmented PR. I added type_name to both yaml and json output. I fail to see how it would break anything.

[nordicjm]

@5frank see failing CI

[nordicjm]

@5frank see failing CI

[fundakol]

It looks good. I could make a few comments about code formatting, but since we don't have any rules defined for this repository, I don't want to block this PR.