SMT2 Incremental: Resolve duplicate and missing declarations

[tautschnig]

Guard send_function_definition against duplicate declare-fun commands by checking identifier_table before sending. Guard define_index_identifiers against duplicate define-fun commands by checking expression_identifiers before defining. Ensure array element dependencies are declared before assertions by calling define_dependent_functions on elements in initialize_array_elements for both array_exprt and array_of_exprt.

Remove no-new-smt tag from byte_extract1, Initialization6, and Pointer_byte_extract4 regression tests that now pass with the fix.

Fixes: #8072

• Each commit message has a non-empty body, explaining why the change was made.
• Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.41%. Comparing base (0170409) to head (ac7c276).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8909   +/-   ##
========================================
  Coverage    80.41%   80.41%           
========================================
  Files         1703     1703           
  Lines       188398   188405    +7     
  Branches        73       73           
========================================
+ Hits        151496   151509   +13     
+ Misses       36902    36896    -6     

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