Support Multiple servers

[FilipeSoares-TomTom]

Currently, the OAClient does not allow to choose which server it uses, but rather it uses the last value of the server list.
This behavior may be seem on the following code:
https://github.com/ndsev/zswag/blob/master/libs/zswagcl/src/openapi-parser.cpp#L402-L403

Where it will iterate over all servers and override the value of config.uri.

However, it would be a good feature to have where one may choose which uri should be used. This could be introduced as a number where the user may be able to inform which server they want to use.

e.g.: if in the creation of a OAClient we have, in its constructor, the parameter "serverNumber" with value 1. the config.uri that used would be the one reflected under the server found on the array space 1