CLI tool improperly recognizing directories

[GravlLift]

When attempting to use command line tool on a directory with a . in the final folder level, the input is incorrectly assumed to be a file. For instance, C:/A.Directory is assumed to be a file, even if it's a folder name.

The root cause is a result of using a regex to determine filenames at:

CSharpToTypeScript/src/CSharpToTypeScript.CLITool/Utilities/FileSystem.cs

Lines 18 to 19 in f36b19e

	public static bool EndsWithFileExtension(this string text)
	=> Regex.IsMatch(text, @"\.\w+$");

I'd propose ditching the use of that extension method and just checking both file/directory existence at the same time.

So change the existing:

CSharpToTypeScript/src/CSharpToTypeScript.CLITool/Validation/InputExists.cs

Lines 20 to 27 in f36b19e

	else if (command.Input.EndsWithFileExtension() && !File.Exists(command.Input))
	{
	return new ValidationResult($"The file path '{command.Input}' does not exist.");
	}
	else if (!command.Input.EndsWithFileExtension() && !Directory.Exists(command.Input))
	{
	return new ValidationResult($"The directory path '{command.Input}' does not exist.");
	}

to simply:

else if (!File.Exists(command.Input) && !Directory.Exists(command.Input))
{
    return new ValidationResult($"The file or directory path '{command.Input}' does not exist.");
}

Might resolve #44?