Allow read-only access to the database

[bernatesquirol]

It would be great to be able to reference as a read-only an already created storage-database.
A use case is using acebase as a "cache" in AWS Lambda, where the writing of files is forbidden, but the reading is allowed.

In short, being able to change this r+->r from function openDatabaseFile in storage-acebase.js

acebase/src/storage-acebase.js

Line 764 in 24ca5f2

this.file = fd = await pfs.open(filename, 'r+', 0).catch(err => {

[appy-one]

I just published v1.16.0 which supports this, simply pass readOnly: true in the storage settings:

const db = new AceBase('mydb', { storage: { readOnly: true } });

Let me know if it works!