www/node: Update to 5.2.0, Create www/node4, Update to 4.2.3

www/node:

• Update PORTVERSION and distinfo checksum (5.2.0) [1]
• Add CONFLICTS to www/node4

www/node4:

• Create www/node4 port for LTS users
• Update www/node4 to 4.2.3 [2]
• Add CONFLICTS to www/node

• Add UPDATING entry for users wishing to remain on LTS (4.x)

Based on:

PR: 204653 [1][2]
Submitted by: Randy Westlund <rwestlun gmail com> [1][2]
Approved by: maintainer <linpct gmail com>