Improve the documentation on how to get started with the Java SDK

[thenswan]

Description:
Improve the documentation on how to get started with the Java SDK:

• improves documentation structure;
• simplifies the documentation;
• adds documentation based on user issues;

This PR also fixes the documentation:

• min Android SDK level;
• running SDK integration tests;
• etc.

Related issue(s):
Fixes #1595 #1622

[thenswan]

My questions for review

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (bf54aa5) 82.20% compared to head (bf64f1d) 82.23%.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #1621      +/-   ##
=============================================
+ Coverage      82.20%   82.23%   +0.02%     
- Complexity      3587     3589       +2     
=============================================
  Files            186      186              
  Lines          11697    11697              
  Branches        1148     1148              
=============================================
+ Hits            9616     9619       +3     
+ Misses          1603     1602       -1     
+ Partials         478      476       -2     

see 2 files with indirect coverage changes

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[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.23%. Comparing base (b86ee46) to head (bf64f1d).
Report is 16 commits behind head on main.

❗ Current head bf64f1d differs from pull request most recent head 9e084d0. Consider uploading reports for the commit 9e084d0 to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1621      +/-   ##
============================================
+ Coverage     82.20%   82.23%   +0.03%     
- Complexity     3588     3589       +1     
============================================
  Files           186      186              
  Lines         11697    11697              
  Branches       1150     1148       -2     
============================================
+ Hits           9615     9619       +4     
+ Misses         1604     1602       -2     
+ Partials        478      476       -2     

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

[sonarqubecloud]

Quality Gate passed

Kudos, no new issues were introduced!

0 New issues
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[agadzhalov]

LGTM