feat: add basic ignore directive, allowing the user to tell anchor to ignore certain packages

[BradLewis]

First pass is just adding it for the apt packages, will do the docker images next and playing around with how it feels.

[TheDen]

Wouldn't this be a %s, since image is a sting?

Suggested change

	t.Errorf("Expected golang:1.22-bookworm but got %v", image)
	t.Errorf("Expected golang:1.22-bookworm but got %s", image)

[TheDen]

Suggested change

	t.Errorf("Expected no error but got %v", err)
	t.Errorf("Expected no error but got %w", err)

[TheDen]

Got GPT-4o to "refactor" this and what it claims (I don't know about readability compared to what you have though)—I'll leave it up to you:

Changes Made:

1.	Replaced strings.TrimLeft with strings.TrimSpace and strings.TrimPrefix for clarity and correctness.
2.	Used strings.Fields to split the command into parts more cleanly.
3.	Simplified the condition checks to enhance readability.
4.	Removed redundant TrimSpace calls in certain places where they were unnecessary.

func parseComment(entry Entry) ([]string, bool) {
	ignoredPackages := []string{}

	if entry.Type != EntryComment {
		return ignoredPackages, false
	}

	command := strings.TrimSpace(strings.TrimPrefix(entry.Value, "#"))
	parts := strings.Fields(command)

	if len(parts) < 2 || parts[0] != "anchor" {
		return ignoredPackages, false
	}

	keyValue := strings.SplitN(parts[1], "=", 2)

	if len(keyValue) < 2 {
		if strings.TrimSpace(keyValue[0]) == "ignore" {
			return ignoredPackages, true
		}
		return ignoredPackages, false
	}

	if keyValue[0] != "ignore" {
		return ignoredPackages, false
	}

	for _, pkg := range strings.Split(keyValue[1], ",") {
		ignoredPackages = append(ignoredPackages, strings.TrimSpace(pkg))
	}

	return ignoredPackages, false
}

[BradLewis]

Turns out this was just wrong lol but thanks chatgpt