#1342 Backport fixes in 6.2 to 6.1

[Hiroshi Miura]

https://github.com/omegat-org/omegat/pull/2356
zs-stpa:topic/stpa/backport/6.1-bugfixes

Backports master bugfixes to releases/6.1, cherry-picked and adapted to old tree layout, full 6.1 suite green:

fix(build): resolve language modules from the provided module libraries #2227 language modules built from source distribution lacked grammar rules and bundled spelling dictionaries (ja adapted: keeps gosen)
fix(core): keep enforced translations highlighted after a team save (SF-RFE-1171) #2188 enforced translations lost highlight after team save (adapted: pre-refactor(core): encapsulate team operations for TMX and glossary as classes in o.o.c.t.operation and pull PreparedFileInfo from RebaseAndCommit #1664 sync path)
fix(matches): treat full-width digits as equivalent when substituting… #2111 full-width digits in fuzzy-match number substitution
fix(ui): correct misleading labels (SF-1516, SF-1265, SF-1731) #2121 misleading labels (SF-1516, SF-1265, SF-1731)
fix(core): return empty collections instead null from NotLoadedProject #2177 NotLoadedProject returned null collections
fix(gui): never surface a blank error message from an exception #2191 blank error messages from exceptions without message
fix(usabilty): user distinguishable plugin names in the preferences->plugins table #2223 bundled plugin list entries showed indistinguishable names/versions
fix(manual): Fix typo in the Appendices > Application Folder chapter(preferred) #2330 manual typo
parts of fix(ci+release): gradle and packaging #2215: Romanian module never shipped (build script misnamed gradle.gradle), Readme-modules.txt copied from nonexistent path

Not ported: fixes for master-only regressions (picocli, JNA, MyMemory constructor, #2126, #2235-follow-up) and reorg-specific build fixes.

[Hiroshi Miura]

[6.1] fix(core): tolerate unknown elements in the project file parser - PR#2302
zs-stpa:topic/stpa/core/tolerant-project-parser-6.1

[Hiroshi Miura]

[6.1] fix(core): create the user scripts folder under its documented name (#2220) - #2382
topic/miurahr/6.1/backport-pr2220