Handle revdeps broken by un-exporting S3 methods

[MichaelChirico]

Filing this issue to help track the downstream PRs filed following breakages from #330

• Replace c.integer64() usage dipterix/readNSx#5
• Call as.integer64 and use dispatch dbverse-org/dbmatrix-r#6
• Use S3 dispatch to avoid calling bit64 S3 methods directly eddelbuettel/nanotime#161
• Use S3 dispatch for integer64 methods Rdatatable/data.table#7753
• GH-50014: [R] Replace imported symbol from bit64 apache/arrow#50015
• Use S3 dispatch for seq() method on integer64 statisticsnorway/ssb-ssbtools#143
• Remove import of S3 method hhoeflin/hdf5r#242
• Rely on S3 dispatch for as.data.frame method MichaelChirico/Rdiagnosislist#1