sync-diff-inspector: consider making struct-equality ignore case and/or column order

[kennytm]

Feature Request

Is your feature request related to a problem? Please describe:

Sync-diff-inspector currently considers the column name's case is significant:

-- upstream
create table t (a int primary key, b int);
-- downstream
create table t (A int primary key, B int);

and the order of columns must be unchanged:

-- upstream
create table u (a int primary key, b int);
-- downstream
create table u (b int, a int primary key);

but these do not actually form material differences. Querying select a, b will produce the same data set on both ends.

Describe the feature you'd like:

Structural-diff should be order-and-case-insensitive.

Describe alternatives you've considered:

The column order may be considered significant if the user uses e.g. select * from t order by 2.

Teachability, Documentation, Adoption, Migration Strategy:

None