Add Support for Array and Key-Value Attributes

[mrasu]

Hi,

Currently, there seems to be no way to add array or key-value attributes using the --attrs argument.
For example, the attribute container.image.tags has a type of string[] (documentation).

It would be helpful to enable creating spans with array attributes such as otel-cli span --attrs "container.image.tags=[aaa,bbb]"

Alternatively, introducing a new argument such as --attrs-json to allow specifying attributes in JSON would also be a viable.