`get_first_mut` lint for element access using zero index

What it does

Similar to the get_first lint but for mutable elements.
When retrieving the first element using get_mut(0) suggest using first_mut(), or front_mut() in case of VecDeque.

I'm not sure if this should be an extension of the existing get_first lint or should get implemented as a separate lint.
If this is considered a useful extension, I can gladly implement it.

Advantage

• Usage of provided functions
• The intend of the code is easier to understand

Drawbacks

No response

Example

let mut v: Vec<i32> = Vec::from([1, 2, 3]);
let _ = v.get_mut(0);

let mut d: VecDeque<i32> = VecDeque::from([1, 2, 3]);
let _ = d.get_mut(0);

Could be written as:

let mut v: Vec<i32> = Vec::from([1, 2, 3]);
let _ = v.first_mut();

let mut d: VecDeque<i32> = VecDeque::from([1, 2, 3]);
let _ = d.front_mut();

Start by inspecting the existing get_first lint and compare its behavior with the get_mut(0) examples for Vec and VecDeque. Add coverage for suggesting first_mut() and front_mut(), and confirm the lint output matches the requested transformations.