Drop support for Homebrew libraries

[jwnimmer-tri]

Homebrew continuous to be a pain point for Drake maintainters.

The "evergreen" nature of it means that our dependencies break with no warning, and require emergency action to fix. There are no "release numbers" so we can't say "we only support release ##### for now".

When we try to submit fixes upstream to improve the situation, even after lengthy debate and reworking the approach they get radio silence from upstream, and closed by their stale-bot (even though it's blocked on upstream, not us).

In short Homebrew is:

• broken, and
• unresponsive

... so it is not a plausible distribution to receive first-class support from the Drake Developer team, in terms of runtime library inter-operability.

For command line tools (cmake, graphviz, etc.), we can still rely on Homebrew, since the tools' command line interface is stable and generally not subject to compatibility shear. The major pain point is the libraries.

Plan

Keep as-is:

• bazelisk
• cmake
• gcc
• glib
• graphviz
• nasm
• pkg-config
• python@3.12
• Xcode

Keep for now (but maybe we build this from source eventually, for better cross-platform lockstep support):

• llvm@15

Build from source:

• eigen
• fmt
• spdlog
• ipopt (and mumps)

Move to requirements.txt (#8392):

• numpy