Allow set the servlet registration in the TLDScanner instead of the constant "jsp"

[Thihup]

In the TLDScanner, it searches for the "jsp" servlet registration.

ServletRegistration reg = ctxt.getServletRegistration("jsp");

While it's not wrong, it would be better if it was possible to change the servlet it searches for.

https://github.com/eclipse-ee4j/wasp/blob/master/src/main/java/org/apache/jasper/runtime/TldScanner.java#L164

[arjantijms]

+1 I encountered that too.

[joakime]

That line of code only looks for registration to get the "validating" init-param value.
Perhaps a context attribute to override that would be a better choice than messing with the spec assigned servlet names. (which we have to change anyway because we can't reference the three letters "jsp" anymore in a future update)