* feat(xml-http-request): new plugin for auto instrumentation for xml-http-request
* chore: new example for xml-http-request and updated examples structure for web
* chore: updating readme
* chore: linting
* chore: fixing origin for tests
* chore: linting
* chore: updating to use b3 format from core
* chore: updates after reviews
* chore: wrong function call
* chore: updating attribute names
* chore: linting
* chore: adding preflight requests, fixing few other issues
* chore: adding image to examples, updating readme
* chore: forcing async to be true, but propagate rest params
* chore: fixing type for open and send function
* chore: fixing format for headers
* chore: reviews
* chore: decrement task count when span exists
* chore: changes after review
* chore: adding weakmap for keeping information connected with xhr
* chore: renaming config param
* chore: not needed cast
* chore: updating title
* chore: refactored xhr, removed tracing dependency, few other issues fixed
* chore: reviews
* chore: refactored for collecting timing resources
* chore: fixes after merging
* chore: reviews
* chore: reviews
Co-authored-by: Mayur Kale <mayurkale@google.com>