Move product version declaration to base

[maximenoel8]

Context

Currently in BV, we need to copy/paste for all modules ( server, proxy and minions ) the product version variable.
The product version is always the same and don't bring information to minion or client modules.
After discussion, we want to declare the product version to only one place and the best place seems to be at the base module level.
From my understanding, the product version is only useful for server, proxy and controller.
I didn't really find use case for the product version for minions / clients.

What does this PR change?

• Move product version declaration at base module level.
• The product version is going to be added to grain template at the host module level and not at the individual module level.
• Modify proxy and server to use the base configuration value if product version is not set at the individual module level.
• Keep the possibility to overwrite the product version at individual module level.
• Update cucumber testsuite module to impact those changes.

Note: individual modules are modules like modules/server/main.tf, modules/minion/main.tf, modules/proxy/main.tf where base module is modules/base/main.tf and host module is backend_modules/libvirt/host/main.tf

Other possibility

Declare the product version at the server level and use the the server_configuration to spread it to all other modules.
It will require more changes because the server_configuration variable is only declare in minion modules.

[meaksh]

Looks good to me. Let's give it a try. Thanks!