enable variable session time for mpcCoreKit

[lwin-kyaw]

• provide custom session time for SessionToken Data based on the clients' subscribe plans
• create new test cases for session time

[lwin-kyaw]

This PR is depended on the torus.js PR, https://github.com/torusresearch/torus.js/pull/129

To make this variable session time works, we may need the following

• updates in torus-utils (torus.js) https://github.com/torusresearch/torus.js/pull/129
• need to include torus.js updates in the following dependencies
  1. CustomAuth (to include latest updates from torus.js)
  2. tKey ServiceProvider (to include CustomAuth dependency (torus.js) update)

Will update the PR again once this, https://github.com/torusresearch/torus.js/pull/129, is merged and published

[lwin-kyaw]

Updated torus.js as torus.js@v12.2.0 has been released.

However, to make this variable session time works properly, we still need the following things

• Update torus.js@v12.20 in CustomAuth. Deps update PR
• Update @tkey/service-provider-torus with CustomAuth updates

Currently, I've used npm overrides to update the peer dependencies in the package.json to make session time works.

"dependencies": {
...
},
"overrides": {
    "@toruslabs/customauth": {
    "@toruslabs/http-helpers": "^6.0.0",
    "@toruslabs/torus.js": "12.2.0"
  },
    "@tkey-mpc/service-provider-torus": {
    "@toruslabs/torus.js": "12.2.0"
  }
},