Add missing BE Service format for PEPPOL export

[Copilot]

PR #6268 implements BE-specific PEPPOL export (Enterprise No. formatting/validation) but only for Sales documents. Service documents would fall through to W1 implementation, missing Belgium Enterprise No. support entirely.

Changes

• Added PEPPOL30 BE Service Validation codeunit (37312) - delegates to BE Sales validation via service→sales conversion (mirrors W1 pattern)
• Extended PEPPOL 3.0 Format BE enum with "PEPPOL 3.0 - BE Service" value (37311) implementing BE Party Info Provider + BE Service Validation
• Updated subscriber to set both "PEPPOL 3.0 Sales Format" and "PEPPOL 3.0 Service Format" on setup insert

Format Selection Flow

// Export codeunits read setup and dispatch to format implementation
Exp. Sales Inv. PEPPOL30   → Setup."PEPPOL 3.0 Sales Format"   → PEPPOL30 BE → FormatEnterpriseNo ✓
Exp. Serv.Inv. PEPPOL30    → Setup."PEPPOL 3.0 Service Format" → PEPPOL30 BE → FormatEnterpriseNo ✓
                                                            (was: PEPPOL30 W1 → No Enterprise No.)

Both document types now apply BE-specific:

• FormatEnterpriseNo: Prepends ISO code to numeric-only enterprise numbers
• Validation: Accepts GLN OR VAT Reg No. OR Enterprise No. (W1 only accepts first two)

Original prompt

Pull Request: #6268

Please analyse how/if this app correctly overrides behaviour of the W1 app when user executes the export of sales or services docs.

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[Groenbech96]

Looks good.