* cmd/dlv: dlv version --verbose
That prints out runtime/debug.BuildInfo read from the dlv binary.
Users can retrieve the same info using `go version -m <path_to_dlv>`
but I think it is convenient to have.
If dlv was built from cloned delve repo:
```
$ ./dlv version -v
Delve Debugger
Version: 1.7.0
Build: $Id: e353a65161e6ed74952b96bbb62ebfc56090832b $
Build Details: go1.16.5
mod github.com/go-delve/delve (devel)
dep github.com/cosiner/argv v0.1.0 h1:BVDiEL32lwHukgJKP87btEPenzrrHUjajs/8yzaqcXg=
...
```
If dlv was built with `go install github.com/go-delve/delve@latest`
with go1.16+, or
`GO111MODULE=on go get github.com/go-delve/delve@latest`
from a clean main module:
```
$ ./dlv version -v
Delve Debugger
Version: 1.7.0
Build: $Id: e353a65161e6ed74952b96bbb62ebfc56090832b $
Build Details: go1.16.5
mod github.com/go-delve/delve v1.7.0
dep github.com/cosiner/argv v0.1.0 h1:BVDiEL32lwHukgJKP87btEPenzrrHUjajs/8yzaqcXg=
...
```
* remove an accidentally added bogus test
