Check for go mod inconsistencies

[lvrach]

Motivation

This PR is meant to solve two problems behind go.mod inconsistencies:

1. Forgetting to commit go.mod after introducing a dependency
2. Differences between go.mod when running go mod tidy with and without enterprise code. This is especially problematic when running Dependabot.

Solution

The solution regarding enterprise code is not ideal, but is a quick one.

The problem with enterprise code is around exclusive dependencies, packages that are only required in enterprise code and not in the open source repo.

To solve this, a new file was added that includes those exclusive dependencies. Following the tools.go trick golang/go#25922.

The github action here runs without enterprise code, thus enforcing that a go.mod generated with enterprise code will be the same with the one without.

Output on error:

[codecov]

Codecov Report

Merging #1368 (5f8d6f9) into master (109a9cb) will increase coverage by 0.39%.
The diff coverage is 47.84%.

@@            Coverage Diff             @@
##           master    #1368      +/-   ##
==========================================
+ Coverage   22.45%   22.84%   +0.39%     
==========================================
  Files         116      116              
  Lines       22148    22244      +96     
==========================================
+ Hits         4973     5082     +109     
+ Misses      16857    16851       -6     
+ Partials      318      311       -7     

Impacted Files	Coverage Δ
event-schema/event_schema.go	0.00% <0.00%> (ø)
event-schema/setup.go	0.00% <0.00%> (ø)
...stomdestinationmanager/customdestinationmanager.go	0.00% <0.00%> (ø)
services/stats/stats.go	0.00% <ø> (ø)
services/streammanager/kafka/kafkamanager.go	0.00% <0.00%> (ø)
services/streammanager/streammanager.go	0.00% <0.00%> (ø)
router/batchrouter/batchrouter.go	31.75% <33.33%> (-0.03%)	⬇️
jobsdb/jobsdb.go	49.71% <71.15%> (+3.58%)	⬆️
gateway/gateway.go	47.92% <100.00%> (+0.17%)	⬆️
jobsdb/jobsdb_utils.go	67.76% <100.00%> (ø)
... and 8 more

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