Support CSV tab delimited data

[jsirianni]

Description of Changes

Using a tab delimiter like (\t) has always been supported but would not woork due to this error:

missing header delimiter in header

This was resolved here #370 but a doc update is required as the new header_delimiter configuration option is required when using tab delimited data with comma delimited header.

Please check that the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• Add a changelog entry (for non-trivial bug fixes / features)
• CI passes

[djaglowski]

Log Files	Logs / Second	CPU Avg (%)	CPU Avg Δ (%)	Memory Avg (MB)	Memory Avg Δ (MB)
1	1000	1.5000341	+0.034510493	125.50795	-2.7164612
1	5000	5.224176	+0.13789606	138.37177	+1.1157074
1	10000	10.551769	+0.44832325	146.61543	+0.49232483
1	50000	50.052746	-1.5169907	178.74043	+4.9579773
1	100000	98.89109	-0.14546967	231.31601	-10.624054
10	100	1.8276254	-0.120746374	134.81601	-0.49353027
10	500	6.1898026	-0.12049484	139.65045	-0.076919556
10	1000	12.068961	+0.017048836	146.43777	-2.138733
10	5000	56.255478	+1.2369919	180.38483	-1.599411
10	10000	108.00877	-0.80501556	225.02695	+2.7808533

[codecov]

Codecov Report

Merging #371 (7d03e96) into master (bc43115) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #371      +/-   ##
==========================================
- Coverage   73.30%   73.27%   -0.03%     
==========================================
  Files         124      124              
  Lines        7977     7977              
==========================================
- Hits         5847     5845       -2     
- Misses       1635     1643       +8     
+ Partials      495      489       -6     

Impacted Files	Coverage Δ
operator/builtin/output/forward/forward.go	60.49% <0.00%> (-1.23%)	⬇️
operator/builtin/output/newrelic/newrelic.go	73.55% <0.00%> (-0.83%)	⬇️

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