build(openapi): phase 3 - generate kotlin clients

[jagpreetsinghsasan]

Is your feature request related to a problem? Please describe.
Currently, the following packages are excluded from kotlin code generation w.r.t. #2272

a. packages/cactus-plugin-htlc-eth-besu
b. packages/cactus-plugin-htlc-eth-besu-erc20
c. packages/cactus-plugin-ledger-connector-iroha
d. packages/cactus-plugin-ledger-connector-iroha2
e. packages/cactus-plugin-ledger-connector-quorum
f. packages/cactus-plugin-ledger-connector-xdai
g. extensions/cactus-plugin-htlc-coordinator-besu

This is mainly due to the problems with usage of oneOf keyword in the above mentioned package's openapi.json files.
Not sure if the v6.x of openapi-generator fixes this, but this issue can have a better clearer resolution once the impact analysis is done for openapi-generator v6.x

Depends on #2220 #2217

[github-actions]

This PR/issue depends on:

• spike(openapi): impact analysis of the upgrade #2220
  By Dependent Issues (🤖). Happy coding!