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 #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() https://github.com/r-lib/rlang/blob/c55f6027928d3104ed449e591e8a225fcaf55e13/R/standalone-cli.R#L405-L419