fix: db-pre-config function failing with pg reserved words

[taimoorzaeem]

When db-pre-config is accidentally set to a pg reserved word like "true", it fails with a confusing error. The function names should be properly quoted to avoid such errors. This commit resolves the mentioned issue by quoting the pre-config function name.

Closes #4380.

[wolfgangwalther]

Don't we have a helper function for this somewhere already?

[steve-chavez]

Maybe

postgrest/src/PostgREST/Query/SqlFragment.hs

Lines 166 to 167 in 3db0561

	escapeIdent :: Text -> Text
	escapeIdent x = "\"" <> T.replace "\"" "\"\"" (trimNullChars x) <> "\""

[taimoorzaeem]

postgrest/src/PostgREST/Query/SqlFragment.hs

Lines 245 to 249 in 6616110

	fromQi :: QualifiedIdentifier -> SQL.Snippet
	fromQi t = (if T.null s then mempty else pgFmtIdent s <> ".") <> pgFmtIdent n
	where
	n = qiName t
	s = qiSchema t

We have this, but it gives a Snippet and not Text. Also, the Config/Database.hs module is currently free of Query and SchemaCache modules, so let's not pollute it with that as it would make the dependency graph even weirder.

I think long term solution would be to have our own Prelude as discussed in #1804 (comment). For now I have handled it by quoting it by a new function quoteQi.