Kraken: Fix WsConnect/WsCancelOrder/TestWsAddOrder race

[thrasher-]

New Issue

Race spotted here: https://github.com/thrasher-corp/gocryptotrader/actions/runs/12462044377/job/34782406720#step:10:594

Looks to be because we're using an authToken global var without any sync.Mutex protection

Context

WARNING: DATA RACE
Write at 0x00000187cda0 by goroutine 197:
  github.com/thrasher-corp/gocryptotrader/exchanges/kraken.(*Kraken).WsConnect()
      /home/runner/work/gocryptotrader/gocryptotrader/exchanges/kraken/kraken_websocket.go:115 +0x519
  github.com/thrasher-corp/gocryptotrader/exchanges/kraken.(*Kraken).WsConnect-fm()
      <autogenerated>:1 +0x33
  github.com/thrasher-corp/gocryptotrader/exchanges/stream.(*Websocket).connect()
      /home/runner/work/gocryptotrader/gocryptotrader/exchanges/stream/websocket.go:355 +0x87b
  github.com/thrasher-corp/gocryptotrader/exchanges/stream.(*Websocket).Connect()
      /home/runner/work/gocryptotrader/gocryptotrader/exchanges/stream/websocket.go:326 +0x9d
  github.com/thrasher-corp/gocryptotrader/internal/testing/exchange.MockWsInstance[go.shape.struct { github.com/thrasher-corp/gocryptotrader/exchanges.Base },go.shape.*github.com/thrasher-corp/gocryptotrader/exchanges/kraken.Kraken]()
      /home/runner/work/gocryptotrader/gocryptotrader/internal/testing/exchange/exchange.go:115 +0x5fb
  github.com/thrasher-corp/gocryptotrader/exchanges/kraken.TestWsAddOrder()
      /home/runner/work/gocryptotrader/gocryptotrader/exchanges/kraken/kraken_test.go:1172 +0x124
  testing.tRunner()
      /opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:1690 +0x226
  testing.(*T).Run.gowrap1()
      /opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:1743 +0x44

Previous read at 0x00000187cda0 by goroutine 260:
  github.com/thrasher-corp/gocryptotrader/exchanges/kraken.(*Kraken).wsCancelOrder()
      /home/runner/work/gocryptotrader/gocryptotrader/exchanges/kraken/kraken_websocket.go:1322 +0x152
  github.com/thrasher-corp/gocryptotrader/exchanges/kraken.(*Kraken).wsCancelOrders.func1()
      /home/runner/work/gocryptotrader/gocryptotrader/exchanges/kraken/kraken_websocket.go:1310 +0xc4

Goroutine 197 (running) created at:
  testing.(*T).Run()
      /opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:1743 +0x825
  testing.runTests.func1()
      /opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:2168 +0x85
  testing.tRunner()
      /opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:1690 +0x226
  testing.runTests()
      /opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:2166 +0x8be
  testing.(*M).Run()
      /opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:2034 +0xf17
  github.com/thrasher-corp/gocryptotrader/exchanges/kraken.TestMain()
      /home/runner/work/gocryptotrader/gocryptotrader/exchanges/kraken/kraken_test.go:58 +0x104
  main.main()
      _testmain.go:255 +0x171

Goroutine 260 (running) created at:
  github.com/thrasher-corp/gocryptotrader/exchanges/kraken.(*Kraken).wsCancelOrders()
      /home/runner/work/gocryptotrader/gocryptotrader/exchanges/kraken/kraken_websocket.go:1308 +0x147
  github.com/thrasher-corp/gocryptotrader/exchanges/kraken.TestWsCancelOrders()
      /home/runner/work/gocryptotrader/gocryptotrader/exchanges/kraken/kraken_test.go:1191 +0x299
  testing.tRunner()
      /opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:1690 +0x226
  testing.(*T).Run.gowrap1()
      /opt/hostedtoolcache/go/1.23.4/x64/src/testing/testing.go:1743 +0x44
==================
--- FAIL: TestWsAddOrder (0.18s)
    testing.go:1399: race detected during execution of test