update alerta application name [unstable]

[xmonader]

right now the alerta is the directory name and in the source.toml it's alerta_ui. let's unify it to alerta and rebuild the frontend

[hossnys]

there is a typo in alerta nav bar "cenral" to be "central "

[abom]

Updated at https://github.com/threefoldtech/jumpscaleX_core/commit/224a233d5d704d5adeb7ffa48d0176eb578fc42f , https://github.com/threefoldtech/jumpscaleX_threebot/commit/7be0af61342992896515991a58d80ac271920b5f and https://github.com/threefoldtech/jumpscaleX_threebot/commit/21954e6d631e964772bc6b957c36dff91830bf91.

ِAlso fixed the typo in navigation bar at https://github.com/threefoldtech/jumpscaleX_threebot/commit/315598243445f8af8ddaa7baa6ae4d4a34e3cb09.

Need to remove old package of zerobot.alerta_ui first (or clean bcdb)

[hossnys]

verified on branch unstable