ui: show tethering status in sidebar

[deanlee]

Displays "Hotspot" and full signal strength in the sidebar when tethering is enabled.

To avoid using a long signal-slot chain from WifiManager to the Sidebar for tethering notifications, a cached Networking *networking instance is used in the sidebar class.
Additionally, the previous width of 100px for displaying the network type was insufficient for "Hotspot," so it has been increased to 200px (width() - 100), and left-aligned with the signal strength display. This slightly changes the layout, but the new alignment is more logical. For example, the "Wi-Fi" text previously extended 8 pixels past the left edge of the signal strength, causing misalignment. Now, the alignment is cleaner.

resolve: #33428

[github-actions]

UI Preview

homescreen : $${\color{red}\text{DIFFERENT}}$$

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offroad_alert : $${\color{red}\text{DIFFERENT}}$$

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onroad_sidebar : $${\color{red}\text{DIFFERENT}}$$

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onroad_wide_sidebar : $${\color{red}\text{DIFFERENT}}$$

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