Add readonly option to Better-SQLite3

[undees]

Better-SQLite3 supports a readonly option on initialization. This PR lets Knex users set that option.

(The automatic code formatter wanted to reflow some lines unrelated to the new code. I've split those automated changes out into a separate commit for clarity and to preserve author attribution on the changed lines.)

Docs PR is in knex/documentation#505.

[coveralls]

Coverage: 92.385% (-0.007%) from 92.392% when pulling 68578c8 on undees:add-readonly-option-to-better-sqlite3 into de2a8a2 on knex:master.

[OlivierCavadenti]

Actions seems broken and we have no checks, I will try to fix that before merging.

[OlivierCavadenti]

Hi,

I have this error in tests, it's seems I can create a database with readonly: false (like before) but with readonly : true;

SqliteError: unable to open database file
    at new Database (node_modules\better-sqlite3\lib\database.js:63:26)
    at Client_BetterSQLite3.acquireRawConnection (lib\dialects\better-sqlite3\index.js:14:12)
    at create (lib\client.js:254:39)

@undees

[undees]

Hi, @OlivierCavadenti. Sorry about this! Looks like the tests were only passing intermittently, depending on whether a previous test case created test/unit/test.sqlite3 before the read-only case looked for it. I've opened #5608 to fix the broken test case, and just for good measure I (re-)verified manually in Node that Better-SQLite3 respects the readonly option.