fix: conn mngr min/max connection values

[alanshaw]

Fixes the case when options are passed with maxConnections and/or minConnections set to undefined:

{
  defaultOptions: {
    maxConnections: Infinity,
    minConnections: 0,
    maxData: Infinity,
    maxSentData: Infinity,
    maxReceivedData: Infinity,
    maxEventLoopDelay: Infinity,
    pollInterval: 2000,
    movingAverageInterval: 60000,
    defaultPeerValue: 1
  },
  options: {
    minPeers: 25,
    maxConnections: undefined,
    minConnections: undefined
  }
}
// These are the values this._options ends up with:
{ maxConnections: undefined, minConnections: undefined }

      1) "before all" hook in "custom config"
(node:67176) UnhandledPromiseRejectionWarning: AssertionError [ERR_ASSERTION]: Connection Manager maxConnections must be greater than minConnections
    at new ConnectionManager (node_modules/libp2p/src/connection-manager/index.js:43:5)
    at new Libp2p (node_modules/libp2p/src/index.js:92:30)
    at Object.module.exports [as libp2p] (src/core/components/libp2p.js:27:10)
    at Proxy.start (src/core/components/start.js:48:31)
    at async Daemon.start (src/cli/daemon.js:63:31)
    at async startHttpAPI (test/http-api/routes.js:29:5)
    at async Context.<anonymous> (test/http-api/routes.js:48:7)

[vasco-santos]

LGTM

[jacobheun]

LGTM