[6.x] n-api: backport to v6.x

• src/node_api_backport.cc and src/node_api_backport.h are added containing stubs for internal APIs used by N-API.

• expectsError() is brought in from master and added to tests/common/index.js.

• N-API tests involving the JS async_hooks module are removed.

• The following commits are partially or completely applied:

f24d0ec2 6a5a9ad6 d20f1f00 5fb6f7f2 cd7d7b15 a03c90b6 33e63fe6 48b5c11b 35c7238b d83f8303 449d1c8e c698017a a29089d7 9cb96ac8 945eb1bb 6e1c25c4 463d1a49 caee112e 755e07cb a1bab826 2bead4ba 1729af2c fe442f6b d3569b62 5ecd2e15 6101bd20 d379db31 a5553971 c2b9048a 629a4476 47f664ee 1286923c 0c16b180 6e312c5c 6c1906ab c1234673 f054855b f7c709fd c90185c1 316b5efd f75bc2c1 3e062762 8938c4c2 91c1ccd8 8a86d9c1 93acfe55 094d92bb 94e29510 246aeaca a893e79a ef49f55e d4cd8c2a 50afd901 24756769 ff9a6bc1 12c8b4d1 dc389bf7 493340f5 8f2c366b a4a9a3de 9cf35255 97ba69f9 959c425a 9b4ab145 51f92b6f e0b1394c 3ee524b1 f2cb78c4 e04d23c1 2336df1b 0736ad47 201ecef7 e07e7081 7be4a84c b3f9b381 6bc82dae a1c08041 f8817890 3594223c 17b818ba 49577269 b33b3e18 84579b1d e6e58fde cec6e216 05e4c1d6 8b902500 a406a32e 3070d53e a8c0a43a 19766547 973c12f6 0c258bdc 92e5f5cc 1a0727d8 8c8c90b7 290315ac cb949057 a10856a7 61e9ba12 78286984 1cdb41f2 c77e6d3f 7efb8f76 6c382dea 82bad0b4 70664bf5 e96b9497 1fe0741e 85d7d97d e6eb5c00 835c3839 b72e7022 af70c3b4 ad664eae f3afe29e 6968eadc aa6fac68 77ca3cb4 9926dfeb 7849b528 e59987c3 57a4cebb 4d1e0862 bb294059 65eefa01 e3f7a54d 73078d60 ac41db4a 598a128f f52c7078 d5b397c9 8f3dab4b 9c6804c1 29df1a87 34cf8ad7 e36917bd c9b6d951 ea927b37 732ae419 f803e77b 0f1888f3 a71d2051 ef28d856 3e18c496 d2913384 ecf6a46d 62e940df ca8a29c3 25291196 01f4d9af c28418a9 df46fcb6 7d9dfdae ddba9693 bd4b7905 062071a9 7a7ac1c6 8ab8c339 fd54b105 bb91879f 43e4efdf effeff18 d9ee297a 19619001 2af49b6c 260cd411 47919b3b f3ef9719 bfade5aa 4a7b7e80 a63b245b 0dd8b9a9 00830116 47c3c587 1b28022d 9516aa19 abfd4bf9 654afa2c 147048a0 2e3fef76 2bbabb1f 0a734fec 73d9c0f9 94a120cf 8aca66a1 cd32b775 a180259e 01422769 deb9622b 972bfe15 42712549 1d968030 42415771 b7a341d7 ba7bac5c 468275ac 6c606916 70b51c8c 9d522225 46f20269 ad5f9875 8bd26d3a 9de2e159 0ec0272e affe0f2d 9decfb15 ca786c37 afd5966f 8fbace16 84602845 0a5bf4ae 491d59da 4a21e398 56e881d0

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines