Factor out service inputs to an own subdirectory/section

[srebhan]

Feature Request

Currently, gathering input plugins and service input plugins (aka listeners) are mixed in the plugins/inputs subdirectory and subsequently share the same TOML prefix. As the naming convention of appending _listener is both bulky and not always followed :-) it is sometimes impossible to tell them apart without looking to the code.

Proposal:

Move all listener/service input plugins to a new subdir plugins/serviceinputs and also change the TOML section to reflect the change. This way it is easier to know what to expect in both editing/reading the config and reviewing code.

Current behavior:

Inputs and service-inputs are mixed.

Desired behavior:

Clearly be able to tell apart both categories without looking at the code.

[powersj]

next steps: talk to the team about this and decide to do this now vs in 2.0 as a breaking change as a part of #9478

[Hipska]

As a con, users will now need to look into 2 lists to find a plugin they need or want to use.

[srebhan]

We could still generate a list where both types are on one page...

[srebhan]

Closing this as we won't get to it in a foreseeable future...