feat(output): add HTML output format

[hogo6002]

Implement https://github.com/google/osv-scanner/issues/1274 Add an HTML output format to display results more effectively, particularly for container scanning. This format retains all the information from the existing table output, including called/uncalled vulnerability details.

New features:

• Groups vulnerabilities by source package and ecosystem. Vulnerabilities from OS images are displayed last by default.
• Provides a total count of vulnerabilities (excluding uncalled vulnerabilities by default).
• Surfaces container scanning metrics, such as layer commands.
• Shows fix version information.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 71.91358% with 91 lines in your changes missing coverage. Please review.

Project coverage is 68.45%. Comparing base (1cde7f4) to head (35ef23b). Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/output/html.go	77.03%	55 Missing and 10 partials :warning:
pkg/reporter/html_reporter.go	26.92%	19 Missing :warning:
internal/utility/severity/severity.go	54.54%	5 Missing :warning:
internal/semantic/parse.go	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1258 +/- ## ========================================== + Coverage 68.38% 68.45% +0.07% ========================================== Files 175 177 +2 Lines 16784 17110 +326 ========================================== + Hits 11478 11713 +235 - Misses 4676 4757 +81 - Partials 630 640 +10 ```

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