Refactored a bit `app run` arguments handling
Replacing compileMode by restxMode (we'll see in a future commit that compileMode should be resolved at `run` time, not at `creation` time)
and introducing appName argument
Introducing "sourcesAvailable" runtime flag during `app run`
appClassName, compileMode & restxMode will be valued depending on it
since if no sources are available (typically, after a `app grab url|gav`), we neither want auto compile nor dev mode
Refactoring to preparing field for `app grab <git url>` implementation
Provided FROM_GIT Grabbing strategy
Moved FROM_GIT strategy *before* FROM_URL since accept() impl
for git could start with http/https (overlapping FROM_URL accept() predicate)
Ensuring given jar is a restx archive before unpacking it
Updated documentation for `app run` with appname & compilation details
Added documentation for `app grab` command
Using ModulesManager's toMrid() instead of custom mrid parsing in FROM_GAV grabbing strategy
Fixed some corner cases in extractExtensionlessFilenameFromUrl()
(urls without dot, or with `?` mark)