feat: add default skip dirs

[owenrumney]

Add a list of default skip directories. These directories are overridden
at a workspace level through the standard vscode settings.

The skipdirs can be added to or removed from, if there are any in the
list when the scan runs, it will add them using the --skip-dirs flag for
Trivy or the Aqua plugin

[Copilot]

Pull Request Overview

This PR adds support for configuring directories to skip during Trivy scans through a new skipDirList configuration option.

• Implements a new SkipDirOption class to handle the --skip-dirs Trivy command flag
• Adds a trivy.skipDirList configuration setting with sensible defaults (e.g., node_modules, .git, etc.)
• Integrates the skip directory option into the Trivy command builder

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/command/options.ts	Implements the SkipDirOption class to apply the --skip-dirs flag with platform-specific quoting behavior
src/command/command.ts	Integrates SkipDirOption into the default Trivy command options list
package.json	Adds trivy.skipDirList configuration with default directories to skip and bumps version to 1.8.8
CHANGELOG.md	Documents the new skip directories feature in version 1.8.8

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