Update ilmbase and openexr to 2.3.0, rename OpenEXR to openexr.

Release notes: https://github.com/openexr/openexr/releases/tag/v2.3.0

Adjust LIB_DEPENDS of all ports that require ilmbase or openexr to chase
the new lower-case spelling of the name, and to omit the version from the
library name to ease future maintenance.

Bump PORTREVISION of all ports that depend on ilmbase or openexr directly,
so that they all get rebuilt on upgrades.

Add patches to graphics/ampasCTL to keep it alive, with (a) ilmbase now
that its Iex::BaseExc class is no longer derived from std::string,
details were given upstream through https://github.com/ampas/CTL/issues/71
and (b) to unwind semicolon/;-lists in cmake that stem from openexr/
ilmbase pkg-config variables.
(Note ampasCTL is unmaintained as FreeBSD port, and upstream,
and I cannot run-time test it.)

Poudriere build tests on 11.2-RELEASE-p1 amd64 of ALL ports depending
directly or indirectly on ilmbase and/or openexr have passed without
regressions. Thus invoking due diligence, I believe I have done the
equivalent of an -exp run, and do not require approval for the dependency
chases to third-party ports.