Make `install_greta_deps()` use an options arg and provide some set defaults

[njtierney]

Related to #664 and #638

This would then look like:

install_greta_deps <- function(py_deps = greta_python_deps(),
                               restart = c("ask", "force", "no"),
                               timeout = 5,
                               ...) {
}

install_greta_deps(py_deps = greta_python_deps())

And would mean you could make a spec and pass it along

aws_install <- greta_python_deps(
  tf_version = "2.11.0",
  tfp_version = "0.19.0",
  keras_version = NULL,
  py_version = "3.8.15"
)
install_greta_deps(py_deps = aws_install)

And also we could create a set of known install sets that work and provide them as objects within greta, e.g.,

# macOS
install_greta_deps(py_deps = .greta_deps_macos)
# windows
install_greta_deps(py_deps = .greta_deps_windows)
# linux
install_greta_deps(py_deps = .greta_deps_windows)
# linux
install_greta_deps(py_deps = .greta_deps_aws)

Or something?

[njtierney]

thought I hadn't saved #666 - this is a duplicate now, so closing