Rename EdgeGatewayServices->EdgeGateway::Configure

So that the class is namespaced under `Vcloud::EdgeGateway` like everything
else. I've renamed it generically to `Configure`, for want of a better name,
because:

- It matches the binary/class names in the other tools.
- It's "action" is to configure a VSE.

There is some overlap with `Vcloud::EdgeGateway::EdgeGatewayConfiguration`
which I've raised [#71220390] to investigate.

I've removed references to the class name in the test "context" blocks
because they are hierarchical and the name comes from the outer "describe"
block.
Relocate schema to edge_gateway directory

In preperation for renaming to Vcloud::EdgeGateway::Schema::*. I'm moving
them separate to the renaming so that git doesn't treat it as an add+rm.
Rename Vcloud::Schema->Vcloud::EdgeGateway::Schema

So that we don't stomp over the main Vcloud namespace. This matches the
directory move in the preceeding commit.
Merge pull request #60 from alphagov/70161966-namespacing

[Fixes #70161966] Rename Vcloud::EdgeGatewayServices and Vcloud::Schema