Add tag deletion from tags list

[nicosomb]

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Documentation	no
Translation	no
CHANGELOG.md	yes/no
License	MIT

Fixed #2952

Need help for design (@Simounet maybe?)

[Kdecherf]

Could you add a screenshot and a prompt for asking the user to confirm the deletion?

[Simounet]

Here is the screen. I used a JS confirm() but this is not a good practice so if I'm motivated enough, I'll do another PR to replace the confirm()'s by a better handler like a11ydialog.
.

[nicosomb]

Thank you @Simounet

[yguedidi]

@nicosomb according to the milestone set, shouldn't this PR target the 2.6.0 branch instead of master? or change the milestone of course! :)