Detect use of `block.timestamp` when running `forge coverage` with `--ir-minimum` enabled

### Component

Forge

### Describe the feature you would like

## Problem

`block.timestamp` is assumed to be constant when `--ir-minimum` (via IR) is enabled, and this leads to false negative failed tests when the tests use the [`warp` cheat](https://getfoundry.sh/reference/cheatcodes/warp).

This can easily create hard-to-debug circumstances - tests that normally pass start failing, and debugging via IR-enabled code is not easy.

For instance, I spent an hour debugging one of our tests.

## Solution

Detect the use of `block.timestamp` in the users' tests, and throw a bespoke warning (or error, if the user specifies so via a config field) about it. Recommend using `vm.getBlockTimestamp()` instead.

### Additional context

## Related

- https://github.com/foundry-rs/foundry/issues/6180
- https://github.com/foundry-rs/foundry/issues/10683
- https://github.com/foundry-rs/foundry/issues/3357