Translatable bulk_email `from_addr` based on user pref. lang

Description

Made the email subject translatable and make it depends on the *user's preferred language*, otherwise it defaults to LANGUAGE_CODE global language.

I could make it defaults to the courses language, What do you think?

This is a follow up for #6889.

Status

Assignee

Unassigned

Reporter

Edx Admin [Administrator]

Labels

Contributor Name

Omar Al-Ithawi

Repo

edx/edx-platform

Customer

Epic Link

None

OSCM Assignee

None

Platform Map Area (Levels 1 & 2)

None

Platform Map Area (Levels 3 & 4)

None

Priority

Unset
Configure