feat(ServletAdapter): Ability remove context path when get method name

[long76]

Refs: #5066

Complex application may have many war-s and do not allow monopolize root context path(/). Add ability to remove context path(usual it's war name) from application server use @WebInitParam or just override getInitParameter for parameter GrpcServlet.REMOVE_CONTEXT_PATH

requestURI = contextPath + servletPath + pathInfo

Usage example:

@WebServlet(urlPatterns = "/*", asyncSupported = true,
        initParams = @WebInitParam(name = GrpcServlet.REMOVE_CONTEXT_PATH, value = "true"))
public class GrpcWebServlet extends GrpcServlet {
...
}

Links:
https://stackoverflow.com/a/42706412
https://coderanch.com/t/610432/certification/getContextPath-getServletPath-getPathInfo

[long76]

don't understand why crash tests) error in test env?

[long76]

don't understand why crash tests) error in test env?

found error - getInitParameter throw exception on tests

[kannanjgithub]

Left a minor comment.

Need a few more changes.

[kannanjgithub]

Some more changes.