Handle case sensitivity of table and column names

[simonvadee]

Description

We have an issue when introspecting the schema using sqlAlchemy (reflection sometimes uses case sensitive or insensitive). Until now we chose to handle everything as lowercase but this makes the code ugly (see database_explorer.py for instance)

See this discussion: https://arkhn.slack.com/archives/G01B1NZC7JQ/p1634036258002900

Additional context

related doc:

https://docs.sqlalchemy.org/en/14/dialects/oracle.html#identifier-casing
https://docs.sqlalchemy.org/en/14/core/metadata.html?highlight=table%20name#sqlalchemy.schema.Table