fix: Fix `inline_const_as_literal` error when the number >= 10
## Description
### The Bug
This PR fixes a small bug in the IDE assistence (`inline_const_as_literal`). When the being-inlined constant is a number and it is greater than or equal to 10, the assistence inserts unexpected string `(0x...)` after the number itself. A simple example is followed:
Current `inline_const_as_literal` changes
```rs
const A: usize = 16;
fn f() -> usize {
A // inline the constant
}
```
into
```rs
const A: usize = 16;
fn f() -> usize {
16 (0x10)
}
```
The bug originates from #14925 & #15306 . #14925 added some unittests, but it just tested the number-inlining behavior when the number is `0`.
50882fbfa2/crates/ide-assists/src/handlers/inline_const_as_literal.rs (L124-L138)
And #15306 modified the behavior of `Const::render_eval` and added the `(0x...)` part after the number (if the number >= `10`). Because of insufficient unittests in #14925, changes about `Const::render_eval` in #15306 introduced this bug with no CI failure.
### The Fix
I think `Const::render_eval` is intended for user-facing value displaying (e.g. hover) and not designed for `inline_const_as_literal`. To fix the bug, I defined a new function named `Const::eval`, which evaluates the value itself faithfully and simply and does nothing else.
## Thanks
Thanks `@roife` for your kind help. Your guidance helped me better understand the code.
77e1969c15