Refactor `chain-client` to remove `fabric-network` dependency

Refactor chain-client to use fabric-gateway instead of fabric-network -

`npm install` or `npm audit` executed in the sdk repository result in 4 high severity warnings that are due to fabric-network no longer receiving updates.

```
jsrsasign <11.0.0
Severity: high
Marvin Attack of RSA and RSAOAEP decryption in jsrsasign - https://github.com/advisories/GHSA-rh63-9qcf-83gf fix available via npm audit fix --force
Will install fabric-network@1.4.20, which is a breaking change node_modules/jsrsasign
fabric-ca-client *
Depends on vulnerable versions of fabric-common
Depends on vulnerable versions of jsrsasign
node_modules/fabric-ca-client
fabric-common >=2.1.1-snapshot.390
Depends on vulnerable versions of jsrsasign
node_modules/fabric-common
fabric-network >=1.4.21-snapshot.1
Depends on vulnerable versions of fabric-common
node_modules/fabric-network

4 high severity vulnerabilities
```