Separate header file for goto-instruction codet types

[kroening]

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a 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).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

Merging #6386 (ea13baf) into develop (998d141) will increase coverage by 0.04%.
The diff coverage is 66.66%.

@@             Coverage Diff             @@
##           develop    #6386      +/-   ##
===========================================
+ Coverage    75.93%   75.97%   +0.04%     
===========================================
  Files         1518     1523       +5     
  Lines       164040   164194     +154     
===========================================
+ Hits        124565   124750     +185     
+ Misses       39475    39444      -31     

Impacted Files	Coverage Δ
...mc/src/java_bytecode/character_refine_preprocess.h	100.00% <ø> (ø)
jbmc/src/java_bytecode/code_with_references.cpp	82.35% <ø> (ø)
...java_bytecode/create_array_with_type_intrinsic.cpp	97.67% <ø> (ø)
...bmc/src/java_bytecode/java_bytecode_instrument.cpp	98.22% <ø> (ø)
...src/java_bytecode/java_bytecode_typecheck_code.cpp	100.00% <ø> (ø)
jbmc/src/java_bytecode/lift_clinit_calls.cpp	100.00% <ø> (ø)
.../unit/java-testing-utils/require_goto_statements.h	20.00% <ø> (ø)
...java_static_initializers/assignments_from_json.cpp	98.28% <ø> (ø)
...a_static_initializers/java_static_initializers.cpp	100.00% <ø> (ø)
...rc/ansi-c/c_typecheck_gcc_polymorphic_builtins.cpp	76.58% <ø> (ø)
... and 39 more

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[tautschnig]

I'm happy with this, but I'd first like to understand how 9a71920 came about? Did we have PRs crossing in the air?

[kroening]

I'm happy with this, but I'd first like to understand how 9a71920 came about? Did we have PRs crossing in the air?

Yes.