* Migrate ActivityHeatmap to Vue SFC

Signed-off-by: Gary Kim <gary@garykim.dev>

* Readd vue compiler alias

Signed-off-by: Gary Kim <gary@garykim.dev>

* Remove unneeded use of v-html

Signed-off-by: Gary Kim <gary@garykim.dev>

Co-authored-by: zeripath <art27@cantab.net>

- lowercase all js filenames except Vue components
- enable new lint rules, mostly focused on shorter code
- autofix new lint violations
- apply misc transformations indexOf -> includes and onevent-> addEventListener

Co-authored-by: Antoine GIRARD <sapk@users.noreply.github.com>

- unvendor vue and vue-calendar-heatmap
- remove unused moment.js leftover from previous heatmap version
- ensure webpack loads the full version of vue
- fix vue devmode warning related to 'searchLimit' type

I wanted to name the chunk heatmap.js but adblockers don't like that
filename [1].

[1] 3899d5dff3/easyprivacy/easyprivacy_general.txt (L2095)