MongoDB: Quoted field name if it contains dollar sign($) or dot(.)

[chhsiao90]

Fixes #3379

[chhsiao90]

Currently, I have no idea for how to add unit test for this issue. Both the embedded mongo server (v3.4.0) and mongo driver not supports dollar sign and dot.

[chhsiao90]

Force push the commit with better commit message.

[ebyhr]

Could you confirm the current behavior on upstream again?
I could access the table having special characters without any change.

> use tpch;
switched to db tpch
>
>
> db.test.insertOne(
... {
...         "client" : "0.0.0.0",
...         "query" : {
...                 "expireAfterSeconds" : {
...                         "$exists" : true
...                 }
...         },
...         "user" : ""
... }
... )

presto> select * from mongodb.tpch.test;
 client  |                query                | user
---------+-------------------------------------+------
 0.0.0.0 | {expireAfterSeconds={$exists=true}} |

[ebyhr]

About testing:

• We can upgrade to mongo:3.6.0 in MongoServer
• There is runCommand method to skip the bson validation.

[chhsiao90]

You are right, I can't reproduce the issue with master branch. It looks like it was already fixed in #1963. Thanks!