Move parse and validate events out to program level

[TwitchBronBron]

Moves the afterFileParse, onValidateFile, and afterFileValidate events into the Program class and out of BrsFile.ts and XmlFile.ts to make things more consistent.

The changes were mostly done to BrsFile.ts, XmlFile.ts, and Program.ts. The other changes are just unit test tweaks to make them work with the changes (i.e. we need to call program.addOrReplaceFile now instead of using the file.parse() function directly to trigger the plugin event.)