Feature/mixfetch disconnect (#3890)

* js error message

* Ability to explicitly disconnect mixfetch

* removed unused import

* added disconnect method directly to sdk package

* simplifying error throw

Co-authored-by: Mark Sinclair <14054343+mmsinclair@users.noreply.github.com>

* added onunload event listener handler

* Using global instance of mixfetch to disconnect

Co-authored-by: Mark Sinclair <14054343+mmsinclair@users.noreply.github.com>

* Bump RC versions

* MixFetch, move unload handler to creation and check for undefined `window`

* Bump RC version

* Force TLS on mixFetch demo

* Add info about working around mixed content errors for mixFetch

---------

Co-authored-by: Mark Sinclair <14054343+mmsinclair@users.noreply.github.com>
Co-authored-by: Mark Sinclair <mmsinclair@users.noreply.github.com>

sdk/typescript/codegen/contract-clients/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@nymproject/contract-clients",
-  "version": "1.2.0-rc.5",
+  "version": "1.2.0-rc.7",
   "description": "A client for all Nym smart contracts",
   "license": "Apache-2.0",
   "author": "Nym Technologies SA",