[13u] RFR 8223260: NamingManager should cache InitialContextFactory

[Dmitry Cherepanov]

JBS: https://bugs.openjdk.java.net/browse/JDK-8223260
Original patch: https://hg.openjdk.java.net/jdk/jdk/rev/92b01977fde2
Webrev for 13u: 
http://cr.openjdk.java.net/~dcherepanov/openjdk13u/8223260/webrev.v0/

The patch applies cleanly but build fails due to using java.io.Serial 
annotation in NamingManager.java (the annotation introduced in 14), 
removed the use of the annotation.

Tested with tier1 and javax/naming tests.

Thanks,

Dmitry