chore: improve examples

[thenswan]

Description:
This PR improves examples:

• add Client#close to each example;
• simplify/optimize exception handling (one general Exception instead of multiple);
• examples perform a clean up (delete created accounts, tokens, etc.);
• updated structure in examples/src/main/resources/com/hedera/hashgraph/sdk/examples;
• updated files in examples/src/main/resources/com/hedera/hashgraph/sdk/examples;
• pass private keys as a parameter only if needed;
• aligned the general structure of examples;
• aligned the approach for handling null values;
• align different error handling approaches and improve error handling where it does make sense (note: examples aren't integration tests, so checks aren't everywhere);
• added possibility of using a logger (the SDK one) and its configuration via .env;
• aligned different logging and printing approaches in examples (structure, style, etc.);
• update examples README.md;
• aligned examples docs;
• optimized wait time in examples;
• optimized tokens and gas spendings in examples;
• removed com.google.errorprone.annotations from examples;
• revisited variable names;
• revisited Hedera objects memos, names, etc.;
• add contracts which used in examples to the resources folder.

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Double check how command task update:addressbooks works.

Closes #1631

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud