feat: make gzip as default content encoding type

[marandaneto]

📢 Type of change

• Bugfix
• New feature
• Enhancement
• Refactoring

📜 Description

feat: make gzip as default content encoding type

💡 Motivation and Context

compress the content of the payload before sending it over the network, so saving some data.

💚 How did you test it?

running and tests passed.
serialization layer is not affected and so didn't need extra tests.
the response content is still a raw JSON, no need to change that as we only get a very small response when there's a 4xx error for example.

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• All tests passing

🔮 Next steps

CI error is due to missing NDK on LGTM analyzer.
https://discuss.lgtm.com/t/android-ndk-v21-1-6352462-is-not-available/2910

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@cc07701). Click here to learn what that means.
The diff coverage is 71.42%.

@@            Coverage Diff            @@
##             master     #433   +/-   ##
=========================================
  Coverage          ?   60.26%           
  Complexity        ?      816           
=========================================
  Files             ?       93           
  Lines             ?     3727           
  Branches          ?      359           
=========================================
  Hits              ?     2246           
  Misses            ?     1328           
  Partials          ?      153           

Impacted Files	Coverage Δ	Complexity Δ
...n/java/io/sentry/core/transport/HttpTransport.java	80.76% <70.73%> (ø)	34.00 <5.00> (?)
...java/io/sentry/core/transport/TransportResult.java	91.66% <100.00%> (ø)	3.00 <1.00> (?)
.../io/sentry/core/transport/CurrentDateProvider.java	66.66% <0.00%> (ø)	2.00% <0.00%> (?%)
...re/src/main/java/io/sentry/core/protocol/User.java	95.12% <0.00%> (ø)	18.00% <0.00%> (?%)
...try-core/src/main/java/io/sentry/core/Session.java	98.64% <0.00%> (ø)	27.00% <0.00%> (?%)
...in/java/io/sentry/core/hints/SessionStartHint.java	100.00% <0.00%> (ø)	1.00% <0.00%> (?%)
...in/java/io/sentry/core/AsyncConnectionFactory.java	100.00% <0.00%> (ø)	1.00% <0.00%> (?%)
...main/java/io/sentry/core/util/ApplyScopeUtils.java	100.00% <0.00%> (ø)	3.00% <0.00%> (?%)
...re/src/main/java/io/sentry/core/util/LogUtils.java	70.00% <0.00%> (ø)	4.00% <0.00%> (?%)
...ore/src/main/java/io/sentry/core/util/Objects.java	100.00% <0.00%> (ø)	2.00% <0.00%> (?%)
... and 85 more

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[rhcarvalho]

Nice removal of some code duplication there!

I just have a suggestion for consideration; will leave it up to another reviewer to approve.

[philipphofmann]

Looks pretty good. Still I have a few comments :)

[philipphofmann]

LGTM