Update HtmlAgilityPack, Pester Tests, refactor

[trackd]

changes

• Update HtmlAgilityPack to 1.11.60 (this should probably be automated in the build)
• Update Pester tests to v5 syntax
• fixes #10, #8
• refactor ConvertFrom-Html
  • added [OutputType()] for intellisense/completion
  • added 'Position = 0' to all input params so it can bind on type
  • re-use htmlagilitypack.htmldocument/htmlweb instance
  • cleanup
  • simplified

this would also simplify if you wanted to add a param for special cases like, in #7

$html = [HtmlAgilityPack.HtmlDocument]@{
	OptionOutputAsXml           = $true
	OptionReadEncoding          = $true
	OptionDefaultStreamEncoding = [System.Text.Encoding]::UTF8
	OptionAutoCloseOnEnd        = $true
	OptionFixNestedTags         = $true
}
$web = [HtmlAgilityPack.HtmlWeb]@{
	AutoDetectEncoding = $false
	OverrideEncoding   = [System.Text.Encoding]::UTF8
}