BitOps plugins should receive lowercase bool values

[LeoDiazL]

Describe the bug
Expected boolean value of true or false, lowercase, but received mixed up values.
In the case of helm deployment, you will get a True for FETCH_KUBECONFIG for Helm plugin.
The reason might be that the plugin defaults defined in schema are passed to the plugins camel-cased (the python way) after yaml parsing.

To Reproduce
Don't have a non-working example, but saw mixed values that might bring trouble in the future.

Expected behavior
Every boolean value should be lower-cased

System info

• BitOps image tag used: latest

Additional context
While working with plugins, saw mixed values used for validation.