Add configurable interceptor for clientId, secret, and baseUrl

[codymikol]

It would be useful for applications that are configurable at runtime to set the clientId, secret, and baseUrl via lambdas

val plaidClient = PlaidClient.newBuilder() .client(plaidCache::getClient) .secret(plaidCache::getSecret) .baseUrl(plaidCache::getBaseUrl) .build()

[phoenixy1]

@stephenjayakar does this get fixed by the beta?