feat: add blocking API to write a batch of records

[pabigot]

Closes #295

Proposed Changes

This extends the blocking API to allow writing line protocol records that have already been combined into a string with newline separators.

Checklist

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

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 91.83%. Comparing base (4218b50) to head (a575f20).
Report is 172 commits behind head on master.

Files with missing lines	Patch %	Lines
api/writeAPIBlocking.go	75.00%	1 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #296      +/-   ##
==========================================
- Coverage   91.87%   91.83%   -0.04%     
==========================================
  Files          23       23              
  Lines        2042     2046       +4     
==========================================
+ Hits         1876     1879       +3     
- Misses        110      111       +1     
  Partials       56       56              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[vlastahajek]

Thanks for the PR. The new function to write a single string is redundant. The WriteRecord function can also take just a single string.
It makes sense to improve this function to skip the loop and also to skip creating a string buffer if there is just a single line.

[pabigot]

OK, I can create a new PR that implements that behavior change, but it's more complicated than it first sounds, and possibly introduces a performance hit by having to check for the conditions under which newlines must be inserted/appended. New API really seems more efficient and less confusing.

[vlastahajek]

A single line doesn't need to have new-line-char. For such a simple case, breaking the API with a new feature seems to be too much.