begin refactoring of request filters to ServerRequestManager

fix bugs and disconnect handling

add jsdoc. remove unnecessary close/reopen of live dev connection.

fix for #4786 add CSSDocument to ServerRequestManager to rewrite HTTP responses on refresh

Refactor ServerRequestManager and all live dev server providers into BaseServer, FileServer, UserServer and StaticServer.

fix jshint errors

code review comments

code review comments from TomMalbran

more jsdoc comments from @TomMalbran

revert move of LiveDevServerManager to keep compatibility with theseus

Adapt older servers (theseus) to work with new API

break compatibility with older servers, including older versions of theseus

fix typo
Merge pull request #4801 from adobe/jasonsanjose/issue-3970

Allow live preview session to live longer after a currentDocumentChange