ICU-22746 Refactor MF2 tests to be data-driven and add JSON lib

This change moves all test strings out of test/intltest/messageformat2test.cpp
and into JSON files, which are parsed/run by code in
a new file, test/intltest/messageformat2test_read_json.cpp .
It also removes the file test/intltest/messageformat2test_fromjson.cpp ,
which contained tests that are now stored in JSON files.

To enable this, a new vendored library is added:
nlohmann/json .
This library is introduced as a dependency for the MF2 tests.
The required part of the library is a single header file,
which is added under icu4c/source/tools/toolutil/.
Also adds a wrapper file for the vendored JSON header file
that defines macros that disable exceptions.

Co-authored-by: Steven R. Loomis <[email protected]>

.cpyskip.txt

@@ -34,6 +34,7 @@ KEYS
 *.intaglio
 *.jar
 *.jpg
+*.json
 *.launch
 *.nrm
 *.odp
@@ -117,3 +118,4 @@ tools/unicodetools/*
 # vendor
 #
 vendor/double-conversion/upstream/*
+vendor/json/upstream/*

LICENSE

@@ -433,6 +433,34 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 ----------------------------------------------------------------------
 
+JSON parsing library (nlohmann/json)
+
+File: vendor/json/upstream/single_include/nlohmann/json.hpp (only for ICU4C)
+
+MIT License
+
+Copyright (c) 2013-2022 Niels Lohmann
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+----------------------------------------------------------------------
+
 File: aclocal.m4 (only for ICU4C)
 Section: pkg.m4 - Macros to locate and utilise pkg-config.
 

icu4c/source/test/intltest/Makefile.in

@@ -49,7 +49,7 @@ fldset.o dadrfmt.o dadrcal.o dcfmapts.o decoll.o dtfmapts.o dtfmrgts.o dtfmtrtts
 dtptngts.o encoll.o escoll.o ficoll.o frcoll.o g7coll.o intltest.o \
 itercoll.o itformat.o itmajor.o itutil.o jacoll.o lcukocol.o \
 loctest.o localebuildertest.o localematchertest.o \
-messageformat2test.o messageformat2test_builtin.o messageformat2test_custom.o messageformat2test_features.o messageformat2test_fromjson.o messageformat2test_icu.o \
+messageformat2test.o messageformat2test_builtin.o messageformat2test_custom.o messageformat2test_features.o messageformat2test_read_json.o messageformat2test_icu.o \
 miscdtfm.o mnkytst.o msfmrgts.o nmfmapts.o nmfmtrt.o \
 numfmtst.o numrgts.o plurults.o plurfmts.o pptest.o regcoll.o restest.o restsnew.o \
 sdtfmtts.o svccoll.o tchcfmt.o selfmts.o \

icu4c/source/test/intltest/intltest.vcxproj

@@ -143,8 +143,8 @@
  <ClCompile Include="messageformat2test.cpp" />
  <ClCompile Include="messageformat2test_custom.cpp" />
  <ClCompile Include="messageformat2test_features.cpp" />
- <ClCompile Include="messageformat2test_fromjson.cpp" />
  <ClCompile Include="messageformat2test_icu.cpp" />
+ <ClCompile Include="messageformat2test_read_json.cpp" />
  <ClCompile Include="miscdtfm.cpp" />
  <ClCompile Include="msfmrgts.cpp" />
  <ClCompile Include="nmfmapts.cpp" />

icu4c/source/test/intltest/intltest.vcxproj.filters

@@ -575,8 +575,8 @@
  <ClCompile Include="messageformat2test.cpp" />
  <ClCompile Include="messageformat2test_custom.cpp" />
  <ClCompile Include="messageformat2test_features.cpp" />
- <ClCompile Include="messageformat2test_fromjson.cpp" />
  <ClCompile Include="messageformat2test_icu.cpp" />
+ <ClCompile Include="messageformat2test_read_json.cpp" />
  </ItemGroup>
  <ItemGroup>
  <ClInclude Include="itrbbi.h">