* meta: rework is_compatible/is_constructible_string_type

These type traits performed an incorrect and insufficient check.

Converting to a std::filesystem::path used to work by accident thanks to
these brittle constraints, but the clean-up performed in #3020 broke them.

* support std::filesystem::path

Fixes #3070

The previous version relied on the existence of an 'iterator' type.

As mentioned in comments, this is not the proper way to do it and
causes issues with certain types (e.g. views from range-v3).

Add a 'is_range' trait that properly detects the return type of
'begin'/'end', and use it in instead.

* Fix assertion failure #3032

* ♻ allow allocators for vectors

* ✅ add regression tests

* Set parent pointers for values inserted via update() (fixes #3007).

* Moved test for #3007 to proper file.

* Enable access to private members in diagnostics unit tests.

* Make style consistent with rest of code.

* Forced amalgamate rerun.

* Refactor test for #3007 so it doesn't use private members. Also extend to test both update() functions.

* Added fix for #3007 to update(const_iterator, const_iterator) as well.

* Added failing example code from #3007 as extra test.

* 📝 update docset generation script

* 📝 update documentation

* Fix #2975

Define JSON_DIAGNOSTICS to 0 if not defined to fix annoying Wundef warnings.

* amalgamated

Changed a potential typo: "charater" -> "character"

🐛 fix parent update for diagnostics with ordered_json

* 🏁 set stack size for some unit tests

Add regression test

Update Travis badge

Fix some extra ";" clang warnings

Updating the Homebrew Command

🚨 fix gdb_pretty_printer failure on basic types

Add header to use value_t

Skip some tests if JSON_Install is not set

Remove outdated json_unit test binary

Avoid duplicate AppVeyor builds

name can be None, and `re.search` fails on `None`;
replaced `re` by `str.startswith` and `str.endswith`

I've submitted a PR on [homebrew/core](https://github.com/Homebrew/homebrew-core/pull/83479) that updates their Formula. After that one is set, we can merge this and let users use the default formula, and we don't have to maintain two separate Formulas.