plugin manager does not distinguish between different instances of the same plugin

[svonjoi]

Issue description

plugin manager does not distinguish between different instances of the same plugin

Minimal reproduction

1. configure plugin inside layout (for example zjstatus)

layout {
    default_tab_template {
        children
        pane size=2 borderless=true {
            plugin location="file:~/.config/zellij/plugins/zjstatus.wasm" {
               <configuration...>
            }
        }
    }

    tab name="~" focus=true {
        pane size="1" cwd="~"
    }
}

2. open 2 tabs. Each tab will have its own zjstatus instance

3. open plugin manager

in the screenshot there are 5 tabs opened, each one with it's zjstatus plugin instance