Cache rlang version in .rlang_cli_compat()?

[DavisVaughan]

I've wondered why lifecycle signaling is so slow, and it looks like there are two main reasons:

• The parse_expr() thing we fixed in Add keep_source to parse_exprs() and friends #1603
• .rlang_cli_compat() checks the rlang package version, which takes quite a while

This seems like a reasonable thing to cache, right?

[DavisVaughan]

Since this is in a standalone file, we can probably mimic .rlang_cli_has_cli()

rlang/R/standalone-cli.R

Lines 405 to 419 in c55f602

	.rlang_cli_has_cli <- local({
	cache <- new.env()
	function(version = "3.0.0") {
	out <- cache[[version]]
	if (is.null(out)) {
	out <- cache[[version]] <<-
	requireNamespace("cli", quietly = TRUE) &&
	utils::packageVersion("cli") >= version
	}
	out
	}
	})