Add support for R 4.4.0

[gaborcsardi]

I.e. Rtools44.

[sjmgarnier]

I get:

> pkgbuild::has_rtools(debug = TRUE)
Found in Rtools 4.4 installation folder
[1] TRUE

but then:

> pkgbuild::rtools_path()
character(0)

[sjmgarnier]

Checking the cache gives:

> pkgbuild:::cache_exists("rtools_path")
[1] TRUE
> pkgbuild:::cache_get("rtools_path")
character(0)

[eduardszoecs]

This still fails because version_info was not updated in 518d65e