chore: vendor v2.0.0-alpha.2 openapi.json files project-wide

This was done by running a modified version of the bump openapi specs script.

The change ensures that there are no $ref's of type REMOTE (when an HTTP/S link is used)
present in any of the openapi.json spec files.

The upside of this change is that we can cross-reference & re-use specifications of other
packages but without the need to have the build's success depend on the internet connection
and the presence of a git tag on upstream repository (which was creating a catch-22 for
the release automation scripts).

Signed-off-by: Peter Somogyvari <peter.somogyvari@accenture.com>

extensions/cactus-plugin-htlc-coordinator-besu/src/main/json/openapi.json

@@ -69,7 +69,7 @@
  },
  "web3SigningCredential": {
  "description": "Web3SigningCredential",
- "$ref": "https://raw.githubusercontent.com/hyperledger/cactus/v2.0.0-alpha.2/packages/cactus-plugin-ledger-connector-besu/src/main/json/openapi.json#/components/schemas/Web3SigningCredential",
+ "$ref": "./vendor_v2.0.0-alpha.2_packages_cactus-plugin-ledger-connector-besu_src_main_json_openapi.json#/components/schemas/Web3SigningCredential",
  "nullable": false
  },
  "inputAmount": {
@@ -147,7 +147,7 @@
  },
  "web3SigningCredential": {
  "description": "Web3SigningCredential",
- "$ref": "https://raw.githubusercontent.com/hyperledger/cactus/v2.0.0-alpha.2/packages/cactus-plugin-ledger-connector-besu/src/main/json/openapi.json#/components/schemas/Web3SigningCredential",
+ "$ref": "./vendor_v2.0.0-alpha.2_packages_cactus-plugin-ledger-connector-besu_src_main_json_openapi.json#/components/schemas/Web3SigningCredential",
  "nullable": false
  },
  "gas": {
@@ -186,7 +186,7 @@
  },
  "web3SigningCredential": {
  "description": "Web3SigningCredential",
- "$ref": "https://raw.githubusercontent.com/hyperledger/cactus/v2.0.0-alpha.2/packages/cactus-plugin-ledger-connector-besu/src/main/json/openapi.json#/components/schemas/Web3SigningCredential",
+ "$ref": "./vendor_v2.0.0-alpha.2_packages_cactus-plugin-ledger-connector-besu_src_main_json_openapi.json#/components/schemas/Web3SigningCredential",
  "nullable": false
  },
  "htlcId": {