fix(common): flaky KeyConverter unit tests

[petermetz]

Describe the bug

Failed once on the CI server but works just fine locally.
https://travis-ci.org/github/hyperledger/cactus/jobs/732084285

To Reproduce

1. Checkout the commit 5938f28
2. npm i && npm run run-ci
3. Observe that succeeds (or does it?)

Expected behavior

Test case outcome should always be consistent across all environments that the tests can be executed in regardless of OS/number of cores/hardware differences in general.

Logs/Stack traces

https://travis-ci.org/github/hyperledger/cactus/jobs/732084285#L5538

Operating system name, version, build:

The Travis CI environment both Node 12 and 14

Hyperledger Cactus release version or commit (git rev-parse --short HEAD):

5938f28

Hyperledger Cactus Plugins/Connectors Used

• Besu

Additional context

I'm suspicious that it may be the key generation in the beginning of the file packages/cactus-common/src/test/typescript/unit/key-converter.test.ts that goes on for too long without a timeout and then crashes the process, but no evidence of this just yet.

[petermetz]

Modified milestone from 2.0.0 to 0.5.0 as per proposal from @sfuji822 (so that we include this in the MVP)