widgets: add a re-useable filtered logread view

Multiple apps introduced their own implementation of a syslog view,
filtered for just their own application logs.  Pull that out as a shared
view.  Some of these had _minor_ style differences, which has been
"standardized" now.  A full "widget" conversion would allow more end app
tuning of that, but is not implemented.

Signed-off-by: Karl Palsson <karlp@etactica.com>

app-nextdns: fix Logs title

Minor typo, introduced in 625abbfd

 (convert simple controllers to
menu.json)

Signed-off-by: Karl Palsson <karlp@etactica.com>

luci-base: implement shared log reader view

Closes #5452

Signed-off-by: Paul Donald <newtwen@gmail.com>