feat: implement very basic ORM

[m4tx]

At this stage, there is an easy way to query, insert, and delete with super simple filters. This is enough of a scaffolding to be able to quickly make it much more advanced.

[codecov]

Codecov Report

Attention: Patch coverage is 85.77982% with 62 lines in your changes missing coverage. Please review.

Files	Patch %	Lines
examples/todo-list/src/main.rs	0.00%	30 Missing ⚠️
flareon/src/db.rs	91.58%	17 Missing ⚠️
flareon/src/db/query.rs	80.00%	9 Missing ⚠️
flareon-macros/src/lib.rs	77.77%	2 Missing ⚠️
flareon-macros/src/model.rs	98.43%	2 Missing ⚠️
flareon/src/request.rs	0.00%	1 Missing ⚠️
flareon/src/router/path.rs	80.00%	1 Missing ⚠️

Flag	Coverage Δ
rust	61.86% <85.77%> (+11.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
flareon-admin/src/lib.rs	100.00% <ø> (ø)
flareon-auth/src/lib.rs	100.00% <ø> (ø)
flareon-macros/tests/compile_tests.rs	100.00% <100.00%> (ø)
flareon/src/db/fields.rs	100.00% <100.00%> (ø)
flareon/src/error.rs	0.00% <ø> (ø)
flareon/src/forms.rs	0.00% <ø> (ø)
flareon/src/lib.rs	0.00% <ø> (ø)
flareon/src/request.rs	0.00% <0.00%> (ø)
flareon/src/router/path.rs	90.47% <80.00%> (ø)
flareon-macros/src/lib.rs	90.90% <77.77%> (-9.10%)	⬇️
... and 4 more

[m4tx]

Eventually we'll have some nice macro that will turn the above into something like:

query!(TodoItem, col(id) == todo_id)

(or something similar)

but I wanted to keep this PR smaller (and honestly, the current API isn't terribly bad either).

[m4tx]

Removed for now as the proc macros currently have the ORM source path hardcoded as ::flareon::db (and honestly I'm not sure about if there is an easy way to un-hardcode this). We might uncouple this eventually if it will make sense in the future, but let's keep the ORM bundled inside the main crate for now.

[m4tx]

Seems like the audit check failure is partially caused by a bug in Cargo: rust-lang/cargo#10801 (comment). A vulnerability was found in rsa package which is not used by as at the moment, but appears in Cargo.lock because it's an optional weak dependency.

The vulnerability in sqlx however is valid, but the fix hasn't been deployed yet. Merging this PR now; we'll update sqlx as soon as the fix is there.