Ensure EtsIR is more three-address-like

[Lipen]

This PR proposes to ensure that EtsIR is three-address code by adding the ensureOneAddress function to ArkIR -> EtsIR conversion process (in Convert.kt). This function extracts nested expressions and field/array references by assigning them to temp locals. In fact, the proposed functionality was already present here, but was duplicated in multiple places. This PR both generalizes it in one place, and also handles nested RHVs in AssignStmt.

[github-actions]

Test results on JDK 19

   83 files  ±0     83 suites  ±0   25m 35s ⏱️ -1s
2 511 tests ±0  2 469 ✅ ±0  42 💤 ±0  0 ❌ ±0 
2 539 runs  ±0  2 497 ✅ ±0  42 💤 ±0  0 ❌ ±0 

Results for commit 8bc63bc. ± Comparison against base commit 864759b.

♻️ This comment has been updated with latest results.

[github-actions]

Test results on JDK 8

   83 files  ±0     83 suites  ±0   33m 22s ⏱️ +7s
2 511 tests ±0  2 466 ✅ ±0  45 💤 ±0  0 ❌ ±0 
2 539 runs  ±0  2 494 ✅ ±0  45 💤 ±0  0 ❌ ±0 

Results for commit 8bc63bc. ± Comparison against base commit 864759b.

♻️ This comment has been updated with latest results.

[github-actions]

Test results on JDK 11

   83 files  ±0     83 suites  ±0   30m 37s ⏱️ -2s
2 511 tests ±0  2 471 ✅ ±0  40 💤 ±0  0 ❌ ±0 
2 539 runs  ±0  2 499 ✅ ±0  40 💤 ±0  0 ❌ ±0 

Results for commit 8bc63bc. ± Comparison against base commit 864759b.

♻️ This comment has been updated with latest results.

[github-actions]

Lifecycle test results

78 tests  ±0   78 ✅ ±0   1m 53s ⏱️ +2s
 7 suites ±0    0 💤 ±0 
 7 files   ±0    0 ❌ ±0 

Results for commit 8bc63bc. ± Comparison against base commit 864759b.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

Attention: Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.

Project coverage is 59.51%. Comparing base (864759b) to head (8bc63bc).

Files	Patch %	Lines
...-ets/src/main/kotlin/org/jacodb/ets/dto/Convert.kt	92.85%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                neo     #245      +/-   ##
============================================
+ Coverage     59.43%   59.51%   +0.08%     
  Complexity     2240     2240              
============================================
  Files           309      309              
  Lines         18301    18288      -13     
  Branches       3261     3260       -1     
============================================
+ Hits          10877    10885       +8     
+ Misses         6349     6329      -20     
+ Partials       1075     1074       -1     

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