Superset i18n: Translate user-provided asset labels, titles, etc.

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Description

"As a client of Aspects, I want dashboards and charts in my native language so that I can understand the data I'm viewing."

Enhance Superset to allow users to provide translations for asset fields like dashboard titles and descriptions, chart titles, descriptions, and axis labels.

Solution must also provide an automated way to extract and update asset translations in a format compatible with from Open edX Transifex.

Currently Aspects works around this issue by creating multiple copies of the standard charts and dashboards for each of our supported languages, with hard-coded translations.

Supporting information

apache/superset#13442

Approach

• Perform a discovery in the form of a [Superset Improvement Proposal|https://github.com/[SIP] Your Title Here (do not add SIP number) apache/superset#30723], and get approved by Superset's contributors.
• Contribute the change to Superset, in phases as needed.

Aspects specifics

• Ensure the solution is backported to the Superset version used by Aspects.
• Replace the Aspects workaround copies with the new translation mechanism, using existing translations where available.

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FYI @bmtcril just creating an issue for this work so I can work on it using CC hours.