audit can't find multi-line yaml strings and raises a ValueError

[OiCMudkips]

Since audit expects a secret to only be on one line, it can't find yaml multi-line strings.

Relevant code snippet:

detect-secrets/detect_secrets/core/audit.py

Lines 604 to 617 in 17918d8

	snippet = CodeSnippetHighlighter().get_code_snippet(
	file_lines,
	secret['line_number'],
	lines_of_context=lines_of_context,
	)
	raw_secret_value = get_raw_secret_value(
	secret,
	plugin_settings,
	io.StringIO(file_content),
	filename,
	)
	snippet.highlight_line(raw_secret_value)

In 0.12.4 and before, this was fine because then get_raw_secret_value would fail, and we would catch the SecretNotFoundOnSpecifiedLineError and handle it properly (i.e. show the user an error and let them move onto the next secret).

In 0.12.5 we made it so that get_raw_secret_value can find multi-line secrets by using plugins' analyze function. However, snippet.highlight_line doesn't know that, and it fails with a ValueError, causing the audit process to terminate.

There are 2 tasks to this:

1. Fix the ValueError causing the program to crash
2. Figure out a method to handle multi-line yaml strings

YAML file: https://i.fluffy.cc/Sm96l1X9PHsvKwPCNNMgBSHjGg56qhTg.html
Generated baseline: https://i.fluffy.cc/4LgX9jCZ9cblGlXJ46bv30hvTFPppz9L.html

[OiCMudkips]

I'll fix the first part, but the second part is probably more involved.