Rename marshall to marshal in all the occurrences

[sincejune]

Description:
Rename the usage of marshall to marshal which includes:

• Variables with Marshaller or Unmarshaller
• Methods with Marshall()
• Files named with marshaller or unmarshaller

Fix comment #2973 (review) and #2973 (comment)

[bogdandrutu]

Please update CHANGELOG with both this change and previous change.

[sincejune]

Update CHANGELOG.

[codecov]

Codecov Report

Merging #2977 (e03b045) into main (e4a0713) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2977   +/-   ##
=======================================
  Coverage   91.64%   91.64%           
=======================================
  Files         312      312           
  Lines       15414    15414           
=======================================
  Hits        14126    14126           
  Misses        881      881           
  Partials      407      407           

Impacted Files	Coverage Δ
exporter/kafkaexporter/otlp_marshaler.go	60.00% <ø> (ø)
receiver/kafkareceiver/jaeger_unmarshaler.go	100.00% <ø> (ø)
receiver/kafkareceiver/otlp_unmarshaler.go	100.00% <ø> (ø)
receiver/kafkareceiver/zipkin_unmarshaler.go	92.59% <ø> (ø)
receiver/otlpreceiver/marshal_jsonpb.go	12.61% <ø> (ø)
exporter/kafkaexporter/factory.go	100.00% <100.00%> (ø)
exporter/kafkaexporter/jaeger_marshaler.go	86.36% <100.00%> (ø)
exporter/kafkaexporter/kafka_exporter.go	100.00% <100.00%> (ø)
exporter/kafkaexporter/marshaler.go	100.00% <100.00%> (ø)
receiver/kafkareceiver/factory.go	100.00% <100.00%> (ø)
... and 3 more

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[sincejune]

@bogdandrutu Would you able to re-run the test? It seems unrelated to my changes.