Proposal: Bump the minimum version of macOS for which we target JavaFX

[Kevin Rushforth]

I propose bumping the minimum version of macOS for which we target 
JavaFX. The current minimum version of macOS is:

ARM (aarch64) : 11.0 -- this is the first version that Apple added ARM 
support
Intel (x64) : 10.12

Apple hasn't supported 10.12 in several years (it went out of support in 
XXXXX), and there is an ongoing *and increasing) cost to our code base 
to keep building and targeting a system that old. See this PR comment 
[1] for the latest example. It is also a little awkward to have a 
different minimum version for the two different chip architectures.

My preference is to change the minimum version for Mac / x64 to be macOS 
11.0, matching both the currently oldest version of macOS supported by 
Apple, and also unifying the minimum for the two chip architectures. We 
could do that in one step or two steps.

Option 1:

JavaFX 21: Bump the minimum (for Intel platforms) to macOS 11

Option 2:

JavaFX 21: Bump the minimum (for Intel platforms) to macOS 10.14
JavaFX 22: Bump the minimum (for Intel platforms) to macOS 11


There are of course other options, but one of those two seems best to 
me. Option 1 is more aggressive, but might cause some concerns, given 
that JavaFX 21 is an LTS. Option 2 is less aggressive, and still gets us 
away from the troublesome 10.12 release (and dropping 10.13 makes it 
easier to consider backporting Metal to 21 some day, since 10.14 is the 
minimum we can support).

Thoughts?

-- Kevin

[1] https://git.openjdk.org/jfx/pull/1089#discussion_r1191393521