Add telemetry event for SSH tunnel connections

[anton-107]

Changes

Why

Tests

[github-actions]

Suggested reviewers

Based on git history of the changed files, these people are best suited to review:

• @ilia-db -- recent work in experimental/ssh/internal/client/

Confidence: low

Eligible reviewers

Based on CODEOWNERS, these people or teams could also review:

@andrewnester, @denik, @pietern, @shreyas-goenka, @simonfaltum

_{Suggestions based on git history of 3 changed files (1 scored). See CODEOWNERS for path-specific ownership rules.}