Upgrade to pebble v1.0.0

[tylerwilliams]

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Dragonboat version

Latest

Expected behavior

Builds against pebble v1.0.0

Actual behavior

Does not build:

# github.com/lni/dragonboat/v4/internal/vfs
internal/vfs/vfs.go:73:9: cannot use p.fs.Create(name) (value of type "github.com/lni/vfs".File) as "github.com/cockroachdb/pebble/vfs".File value in return statement: "github.com/lni/vfs".File does not implement "github.com/cockroachdb/pebble/vfs".File (missing method Fd)
internal/vfs/vfs.go:88:13: cannot use f (variable of type "github.com/lni/vfs".File) as "github.com/cockroachdb/pebble/vfs".File value in argument to opt.Apply: "github.com/lni/vfs".File does not implement "github.com/cockroachdb/pebble/vfs".File (missing method Fd)
internal/vfs/vfs.go:90:9: cannot use f (variable of type "github.com/lni/vfs".File) as "github.com/cockroachdb/pebble/vfs".File value in return statement: "github.com/lni/vfs".File does not implement "github.com/cockroachdb/pebble/vfs".File (missing method Fd)
internal/vfs/vfs.go:95:9: cannot use p.fs.OpenDir(name) (value of type "github.com/lni/vfs".File) as "github.com/cockroachdb/pebble/vfs".File value in return statement: "github.com/lni/vfs".File does not implement "github.com/cockroachdb/pebble/vfs".File (missing method Fd)
internal/vfs/vfs.go:115:9: cannot use p.fs.ReuseForWrite(oldname, newname) (value of type "github.com/lni/vfs".File) as "github.com/cockroachdb/pebble/vfs".File value in return statement: "github.com/lni/vfs".File does not implement "github.com/cockroachdb/pebble/vfs".File (missing method Fd)

Steps to reproduce the behavior

go get -u github.com/cockroachdb/pebble@v1.0.0
go build

I had a quick look at doing this myself but I think there are several changes required to lni/vfs. It would be great to get this in before releasing v4 so that a dragonboat depends on a more stable version of pebble.

[tylerwilliams]

I had a go at this today when I had a few more minutes. The simplest thing seems to work; lni/vfs#3 implements the new interface in the VFS package and #339 fixes up a few small issues and uses the new VFS package.

LMK what you think.

[lni]

Very happy to see Pebble finally got itself a Go compatible module version number. Will look into it and merge all related PRs as long as they don't break other stuff.

Thanks for the PRs.