Allow combining AutoCLI commands and existing commands

[julienrbrt]

Right now, client/v2 can enhance a module command when it is not defined in the application.
However, currently there is no possibility to enhance only the non-existing commands with autocli. It is all or none the module queries / txs.

We should allow users to combine both AutoCLI and manual commands in a module, where AutoCLI only adds non-existing commands within the module queries/txs.

This allows users to progressively migrate to AutoCLI without losing flexibility.