Validate and restore listeners on startup, and allow deletion if not found in connector

[peterbroadhurst]

Had a situation where we wanted to restore fresh listeners for custom contracts on a FireFly core service, and had assumed FireFly core would re-create the listeners. So deleted them on the EVMConnect runtime directly and restarted FF.

Found related issues, that meant we had to go into the FF DB and remove the contract listeners directly (and have the app recreate them):

1. FireFly did not recreate the listener. This seems a little inconsistent with both the BatchPin listener, and the listeners of the token connectors...
   • Proposing in this PR that we automatically recreate the listeners where possible (only Ethereum in this PR, due to existing limitations around the Fabric connector integration where it does not have existing query support to check existence)
2. The API could not be used to delete the listener, because when EVMConnect returned a 404 FireFly failed the DELETE API.
   • This seemed like a straight bug to me. Due to the return of status being interface{} and the complexity of a nil check there, we're adding an extra bool to whether it's found or not (Fabric always returns true)
3. Found in testing this change, that the check on existence of a contract listener with the same parameters was not working, passing in a []byte for the location rather than string

[peterbroadhurst]

Adding fix for this build failure:

--- FAIL: TestStartLegacyAdminConfig (0.01s)
    server_test.go:116: 
        	Error Trace:	/home/runner/work/firefly/firefly/internal/apiserver/server_test.go:116
        	Error:      	Received unexpected error:
        	            	listen tcp 127.0.0.1:6000: bind: address already in use
        	            	FF00151: Unable to start listener on 127.0.0.1:6000: %!s(MISSING)
        	            	github.com/hyperledger/firefly-common/pkg/i18n.WrapError
        	            		/home/runner/go/pkg/mod/github.com/hyperledger/firefly-common@v1.2.3/pkg/i18n/errors.go:42
        	            	github.com/hyperledger/firefly-common/pkg/httpserver.(*httpServer).createListener
        	            		/home/runner/go/pkg/mod/github.com/hyperledger/firefly-common@v1.2.3/pkg/httpserver/httpserver.go:97
        	            	github.com/hyperledger/firefly-common/pkg/httpserver.NewHTTPServer
        	            		/home/runner/go/pkg/mod/github.com/hyperledger/firefly-common@v1.2.3/pkg/httpserver/httpserver.go:82
        	            	github.com/hyperledger/firefly/internal/apiserver.(*apiServer).Serve
        	            		/home/runner/work/firefly/firefly/internal/apiserver/server.go:110
        	            	github.com/hyperledger/firefly/internal/apiserver.TestStartLegacyAdminConfig
        	            		/home/runner/work/firefly/firefly/internal/apiserver/server_test.go:115
        	            	testing.tRunner
        	            		/opt/hostedtoolcache/go/1.18.10/x64/src/testing/testing.go:1439
        	            	runtime.goexit
        	            		/opt/hostedtoolcache/go/1.18.10/x64/src/runtime/asm_amd64.s:1571
        	Test:       	TestStartLegacyAdminConfig

[nguyer]

I wonder if, rather than storing "latest" we should resolve what the latest block number is at the time, then store that? This is out of scope for this PR, but may be worth thinking about for better determinism.

[nguyer]

One minor thing which I think will result in a misleading log message, but other than that, looks good!

[nguyer]

I think we need to increment verifyCount right here. Currently it doesn't look like it's ever updated.