Add WildcardPattern ToRegex method

[ThomasNieto]

Summary of the new feature / enhancement

As a user I want to be able to convert a user provided PowerShell wildcard pattern into a regex pattern for use in programs that accept regex.

Proposed technical implementation details (optional)

It looks like there is already a converter for this but just needs to be made public.

PowerShell/src/System.Management.Automation/engine/regex.cs

Lines 79 to 86 in 60dc724

	internal string PatternConvertedToRegex
	{
	get
	{
	var patternRegex = WildcardPatternToRegexParser.Parse(this);
	return patternRegex.ToString();
	}
	}

PowerShell/src/System.Management.Automation/engine/regex.cs

Lines 936 to 953 in 60dc724

	/// <summary>
	/// Parses a <paramref name="wildcardPattern"/> into a <see cref="Regex"/>
	/// </summary>
	/// <param name="wildcardPattern">Wildcard pattern to parse.</param>
	/// <returns>Regular expression equivalent to <paramref name="wildcardPattern"/></returns>
	public static Regex Parse(WildcardPattern wildcardPattern)
	{
	WildcardPatternToRegexParser parser = new WildcardPatternToRegexParser();
	WildcardPatternParser.Parse(wildcardPattern, parser);
	try
	{
	return ParserOps.NewRegex(parser._regexPattern.ToString(), parser._regexOptions);
	}
	catch (ArgumentException)
	{
	throw WildcardPatternParser.NewWildcardPatternException(wildcardPattern.Pattern);
	}
	}

[santisq]

This would be great to have as a public API I think, for the time being, with ClassExplorer this can be obtained very easily:

$wp = [WildcardPattern]::new('foo*bar*.ext')
$member = $wp | Find-Member -Name PatternConvertedToRegex -Force
$member.GetValue($wp)

# Outputs: ^foo.*bar.*\.ext$

[SeeminglyScience]

The Engine WG reviewed this, we agree that the method should be made public but a PR to make this change should include tests to verify that it works as expected.

[ThomasNieto]

@SeeminglyScience why is this being flagged for closure even though it has up for grabs?