[battery-threshold][FEATURE] Let open Battery Threshold from Launcher

[hongquan]

Submission checklist

• I have searched existing issues and confirmed this has not been requested before.
• I have checked existing pull requests for similar changes.
• This is about a community plugin, not about Noctalia itself (those belong in the noctalia repo).

Plugin

battery-threshold

Feature type

Integration support

Feature summary

Let open Battery Threshold panel from Noctalia Launcher

Motivation / use case

Currently, the only way to open Battery Threshold panel is to add its widget to the topbar, then click.
But it is a waste of topbar space, because we don't often need to access Battery Thresold.

Proposed solution

noctalia-dev/noctalia#3798 (comment)

Alternatives considered

No response

References / related projects

No response

Additional context

No response

[github-actions]

CC @damian-ds7