[TG-9219] Add new option --ignore-manifest-main-class

[antlechner]

If the option is specified, any main class that may be specified in the manifest file of a JAR will be ignored in the class loading stage.
This is useful when we want to e.g. load all classes in a JAR file, some of which may not be referenced from the specified main class.

• Each commit message has a non-empty body, explaining why the change was made. (except for regression test commit)
• n/a 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).
• 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-io]

Codecov Report

Merging #5068 into develop will increase coverage by <.01%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           develop    #5068      +/-   ##
===========================================
+ Coverage    69.61%   69.61%   +<.01%     
===========================================
  Files         1316     1316              
  Lines       109087   109091       +4     
===========================================
+ Hits         75939    75944       +5     
+ Misses       33148    33147       -1

Impacted Files	Coverage Δ
jbmc/src/java_bytecode/java_bytecode_language.h	72.72% <ø> (ø)	⬆️
jbmc/src/java_bytecode/java_bytecode_language.cpp	93.75% <100%> (+0.05%)	⬆️
jbmc/src/java_bytecode/ci_lazy_methods.cpp	100% <0%> (+0.74%)	⬆️

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[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: f3c9735).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/125212217

[antlechner]

I generalised the regression test as requested by @segun3d, to use two different packages in the jar file.

[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: cbe9391).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/125261944

[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: a49fd3d).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/125275386

[peterschrammel]

@antlechner, the failing regression test should be fixed by rebasing.

[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: 974f6a0).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/125499169

[antlechner]

More tests added as requested by @segun3d (one with --main-class, one with --function, one with both, and one without --ignore...).

[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: 7fabc9d).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/125790120

[allredj]

⚠️
This PR failed Diffblue compatibility checks (cbmc commit: 54ee1a9).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/125924156
Status will be re-evaluated on next push.
Common spurious failures include: the cbmc commit has disappeared in the mean time (e.g. in a force-push); the author is not in the list of contributors (e.g. first-time contributors); compatibility was already broken by an earlier merge.

[yumibagge]

QA review [Passed]

https://diffblue.atlassian.net/browse/TG-9219?focusedCommentId=24275&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-24275

Added regression tests looks well covered. Many thanks 🙂