We've got a report from a user that erigon fails to run with this error:
```
/opt/erigon/releases/latest/bin/erigon: error while loading shared libraries: libsilkworm_capi.so: cannot open shared object file: No such file or directory
```
On this system erigon is executed using a service-account user which has
no permission to access the build user's $HOME where the
libsilkworm_capi.so resides (inside $GOPATH/pkg/mod).
This adds a support to silkworm-go to look for the library relative to
the executable path on Linux:
d4ec8a8bce
and a new `make DIST=<path> install` command which copies both the
library and erigon binary to any destination.
