Add support for default column values in engine

[ebyhr]

Description

This PR adds support for the DEFAULT clause with literal values when creating a new table or adding a column.
The SHOW CREATE TABLE statement now includes the specified default values.
These defaults are respected in INSERT and MERGE operations.
Non-literal expressions such as <datetime value function>, USER, and similar are not supported in this PR.

<default clause> ::=
  DEFAULT <default option> 

<default option> ::=
    <literal> 
  | <datetime value function> 
  | USER
  | CURRENT_USER
  | CURRENT_ROLE
  | SESSION_USER
  | SYSTEM_USER
  | CURRENT_CATALOG
  | CURRENT_SCHEMA
  | CURRENT_PATH
  | <implicitly typed value specification> 

Release notes

## General, Memory
* Add support for default column values. ({issue}`25679`)

[ebyhr]

Addressed comments.

[martint]

The general approach looks good now. @kasiafi can you take a look?

[ebyhr]

(Rebased on master to resolve logical conflicts)

[kasiafi]

LGTM

@martint PTAL

[ebyhr]

Rebased on master to resolve conflicts.

[ebyhr]

CI hit #14895

[ebyhr]

Let me merge this PR since Martin has agreed on the general approach. I'll follow up with additional PRs if needed.