feat(currency-format): per-currency symbol position for auto-detect currency

[kleostouraiti]

Problem

Dynamic / Auto-detect currency formatting (#36416) correctly resolves which ISO 4217 symbol to show, but symbol placement (prefix vs suffix) is inconsistent:

1. Chart controls often persist symbolPosition: "suffix" even when the prefix/suffix dropdown appears empty (upstream default). GBP and USD charts then render as 1,234 £ instead of £ 1,234.
2. With Auto-detect and an unset position, every currency inherits the same global default (suffix), which does not match common conventions (e.g. EUR often shown as 1.234,56 €, USD/GBP as $1,234 / £1,234).

Proposed behavior

Case	Behavior
User selects prefix	Always prefix
User selects suffix	Suffix only for currencies in a small default suffix set (initially EUR); USD/GBP still prefix
Position unset / auto-detect	EUR → suffix; other ISO codes → prefix

Scope

• @superset-ui/core CurrencyFormatter and utils.ts (auto-detect path)
• Unit tests in superset-ui-core/test/currency-format/

Out of scope (for now)

• Instance-level config for suffix currency list (could follow in a separate PR)
• Changing D3 number locale / D3_FORMAT (orthogonal)

Context

We hit this in production with multi-currency datasets (currency code column + Auto-detect). Happy to contribute a PR if this direction aligns with maintainers.

[139Vaibhav]

🤖 Devin has been assigned to this issue.

Session: https://app.devin.ai/sessions/64f06c06f9e24bae9317cac158e2c778

I will post a follow-up comment when a pull request is ready.