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GH-37941: [R][CI][Release] Add checksum verification for pre-compiled binaries (#38115)

### Rationale for this change

This change is to restore parity with the previous solution on macOS (brew does cs validation) and improve security for windows and linux. This also align with CRAN policy.

### What changes are included in this PR?

This PR adds a script that can be run after the arrow release (once all files have been pushed to the artifactory) before the CRAN submission to download the checksum files for the pre-compiled binaries which are already added through the usual release. *libs.R have been extended to use these checksum files to validate the downloaded binaries.

### Are these changes tested?

The r-binary-packages nightlies generate checksums and use them when building binary packages, this way the code path is tested. They do not modify the actual src package though.

### Are there any user-facing changes?
no (outside of log messages)
* Closes: #37941

Authored-by: Jacob Wujciak-Jens <jacob@wujciak.de>
Signed-off-by: Nic Crane <thisisnic@gmail.com>