Space out stored headers so SQL Server search finds ids next to emails and URLs

[warwickschroeder]

What this fixes

Since phrase search, SQL Server could not find a message id followed by an email- or URL-valued header, so ServicePulse could not open that message. Headers are now stored with whitespace between entries on the error and audit persisters. Bodies are unchanged, so search inside a compact JSON body still misses emails and URLs, and rows stored before this keep the old layout.

• Headers are written one entry per line, as "key": "value".
• Reading accepts both layouts, so stored rows still load.
• PostgreSQL is unaffected; its search never had the problem.
• Stored headers grow by about 2 to 3 percent: one space and one line break per header, about 110 to 160 bytes for 26 headers on SQL Server. Bodies, API responses and the full-text index stay the same size.

How to reproduce

On SQL Server, ingest a message whose id is followed by a header such as NServiceBus.ReplyToAddress: Sales@web01.corp.example.com. Searching the id finds nothing, and opening it by id says it cannot be found.

Tests

• ServiceControl.Persistence.Tests/EFCore/MessagesViewDataStoreTests: an id followed straight away by an email-like reply-to address is found, on SQL Server and PostgreSQL.
• ServiceControl.Audit.Persistence.Tests/EFCore/EFQueryTests: the same for audit.