`//pkg/tcpip/link/rawfile` is a package to deal with raw socket and file FDs.
It is not only used for Netstack, but rather just generally useful raw file
manipulation stuff.
This change removes the Unix-error-to-`//pkg/tcpip`-error translation step
from its functions; this is now the responsibility of its callers. Callers
within Netstack now do the translation by themselves; the translation
function is moved to `//pkg/tcpip`.
This allows the `//pkg/tcpip/link/rawfile` package to not depend on
`//pkg/tcpip`, which in turn means the `//pkg/eventfd` package
(which depends on `rawfile`) no longer transitively depends on
`//pkg/tcpip`, which in turns means the `//pkg/unet` package (which
depends on `//pkg/eventfd`) no longer transitively depends on
`//pkg/tcpip`, which in turns means that the `//pkg/eventchannel`
package (which depends on `//pkg/unet`) no longer transitively
depends on `//pkg/tcpip`, which in turns means that the `//pkg/metric`
package (which depends on `//pkg/eventchannel`) no longer transitively
depends on `//pkg/tcpip`, which finally means that the `//pkg/metric`
package can be used within `//pkg/tcpip`. \o/
This changes does not make it use it, it just moves `rawfile`.
PiperOrigin-RevId: 647943618
Etienne Perot