enable json1 extension

[kaizhu256]

motivation

• fixes JSON1? #259 (json is used an awful lot in javascript ;)
• maintain feature-parity with node-sqlite3, which includes json1 by default

impact on file-size

comparing build-artifacts between this pr and master,
there's a 2.68% increase in filesize for sql-wasm.wasm:

file                          master    pr.json1  size_increase
----                          --------  --------  ----------------
worker.sql-asm-debug.js       10868144  11054003  +185859 (1.71 %)
sql-asm-debug.js              10865661  11051520  +185859 (1.71 %)
sql-asm-memory-growth.js       2387025   2453699   +66674 (2.79 %)
worker.sql-asm.js              2386050   2452724   +66674 (2.79 %)
sql-asm.js                     2383567   2450241   +66674 (2.80 %)
sql-wasm-debug.wasm            1223845   1256667   +32822 (2.68 %)
sql-wasm.wasm                  1137969   1168425   +30456 (2.68 %)
worker.sql-wasm-debug.js        284549    284549        0
sql-wasm-debug.js               282066    282066        0
worker.sql-wasm.js               56224     56224        0
sql-wasm.js                      53741     53741        0

[lovasoa]

Thank you @kaizhu256 !

[kaizhu256]

woot!

[damion-add-on-depot]

Is there a list of all supported extensions?