feat: add DataToPoint utility to convert a custom struct to a write Point

[sranka]

Proposed Changes

This PR adds a new write.DataToPoint function that converts custom structures to write.Point, the code uses the tags/annotations from v3 client proposal to map structure fields to line protocol parts.

See also https://github.com/influxdata/influxdb-client-go/pull/389

Checklist

• [x] CHANGELOG.md updated
• [x] Rebased/mergeable
• [x] A test has been added if appropriate
• [x] Tests pass
• [x] Commit messages are in semantic format
• [x] Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (c1da0c5) 92.72% compared to head (425a783) 92.94%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #394 +/- ## ========================================== + Coverage 92.72% 92.94% +0.21% ========================================== Files 23 25 +2 Lines 2242 2310 +68 ========================================== + Hits 2079 2147 +68 Misses 123 123 Partials 40 40 ```

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