Add parametrized queries

[tonykploomber]

Describe your changes

1. Disable the default IPython var_expand for {a}, $a case

We disable the default variable substitution by adding @no_var_expand to the line_magic, since we still need to support the default variable substitution + new parametrized fashion in recent versions, we move that parsing part in the SQLCommand class

2. Add _var_expand in SQLCommand class

The logic for supporting {a}, $a (IPython) + {{a}} (new param feature) variable substitution is:

1. Handle the line & cell original string by jinja2 (new param feature)
2. Handle the line & cell original string by IPython var_expand native function to support the IPython way

This execution order matters, since {a} is the subset of {{a}}, we need to handle the {{a}} case before being handled by {a}

P.S. After those string are parsed, the :a part will still be kept, since it's handled by SQLAlchemy engine

Conclusion

This PR fulfill three requirements:

1. Add @no_var_expand to the execute line magic. We handle the var_expand by ourself
2. When there is variable substitution in {a}, $a, :a. We display message (can be discussed)

Please aware the variable substition as {a}, $a, and :a format has been deprecated.
Use {{a}} instead.

3. Support variable substitution in {{a}} fashion, the values will fetch from user name space now

Preview

:a - with deprecated message

{a} - with deprecated message

$a - with deprecated message

{{a}} - new parameter - consumed value from existing scope

Follow up

We need to support the arg --param & --use-global with {{a}} format in next PR

Issue ticket number and link

Closes #93

Checklist before requesting a review

• I have performed a self-review of my code
• I have added thorough tests (when necessary).
• I have added the right documentation in the docstring and changelog (when needed)

---

📚 Documentation preview 📚: https://jupysql--137.org.readthedocs.build/en/137/

[edublancas]

also, let's add a tutorial in our docs describing this feature, and include the link to it

e.g., https://jupysql.ploomber.io/en/latest/user-guide/templating.html

https://github.com/ploomber/contributing/blob/main/documentation/notebooks.md

also in the current documentation where we explain the variable substitution, let's add a deprecation notice

```{versionchanged} 0.5.7
This has been deprecated use '{{a}}' [and add link to the new tutorial
```

[edublancas]

ah and one more thing: let's add a new document in the user guide where we list the incompatibilities with the ipython-sql project. just 1-2 sentences saying we use {{a}} instead of the old method and a link to the tutorial

[tonykploomber]

New template page in user-guide: https://jupysql--137.org.readthedocs.build/en/137/user-guide/template.html
Add deprecation notice in intro: https://jupysql--137.org.readthedocs.build/en/137/intro.html#variable-substitution

incompatibilities:

Please ignore the latest build fail, since the new page user-guide/template.html haven't deployed to jupysql.ploomber.io, it won't pass the broken-links action in our CI

[idomic]

Looks like the CI is failing on broken links

[tonykploomber]

Looks like the CI is failing on broken links

Yes. this is expected, #137 (comment)

Since we added the new page user-guide/template.md, and also referred it in another page (vs.md), but the template page haven't deployed to jupysql.ploomber.io, so it failed on broken-link

The second newest commit 6c4d9cb is a success build, since it it's without referring the template page. The latest commit is with that

[tonykploomber]

The see more link wouldn't pass the broken-link, revert for now

[edublancas]

looks like the docs are failing, my guess is that this is due to the new jupyter book version: https://github.com/executablebooks/jupyter-book/releases

let's pin to <0.14.0 and see if that fixes it

[tonykploomber]

@edublancas
Sync with latest master, you can review again!