From<u8> for u16 implementation (#5815)

## Description
Adds From<u8> for u16

Partially addresses #5797

## Checklist

- [x] I have linked to any relevant issues.
- [x] I have commented my code, particularly in hard-to-understand
areas.
- [x] I have updated the documentation where relevant (API docs, the
reference, and the Sway book).
- [ ] If my change requires substantial documentation changes, I have
[requested support from the DevRel
team](https://github.com/FuelLabs/devrel-requests/issues/new/choose)
- [x] I have added tests that prove my fix is effective or that my
feature works.
- [x] I have added (or requested a maintainer to add) the necessary
`Breaking*` or `New Feature` labels where relevant.
- [x] I have done my best to ensure that my PR adheres to [the Fuel Labs
Code Review
Standards](https://github.com/FuelLabs/rfcs/blob/master/text/code-standards/external-contributors.md).
- [x] I have requested a review from the relevant team or maintainers.

---------

Co-authored-by: IGI-111 <igi-111@protonmail.com>

Author: SwayStar123

sway-lib-std/src/primitive_conversions/u16.sw

@@ -1,6 +1,6 @@
 library;
 
-use ::convert::TryFrom;
+use ::convert::{From, TryFrom};
 use ::option::Option::{self, *};
 
 impl u16 {
@@ -15,6 +15,28 @@ impl u16 {
     }
 }
 
+impl From<u8> for u16 {
+    /// Casts a `u8` to a `u16`.
+    ///
+    /// # Returns
+    ///
+    /// * [u16] - The `u16` representation of the `u8` value.
+    ///
+    /// # Examples
+    ///
+    /// ```sway
+    ///
+    /// fn foo() {
+    ///     let u16_value = u16::from(0u8);
+    /// }
+    /// ```
+    fn from(u: u8) -> Self {
+        asm(r1: u) {
+            r1: u16
+        }
+    }
+}
+
 impl TryFrom<u32> for u16 {
     fn try_from(u: u32) -> Option<Self> {
         if u > u16::max().as_u32() {
@@ -59,6 +81,20 @@ impl TryFrom<u256> for u16 {
     }
 }
 
+#[test]
+fn test_u16_from_u8() {
+    use ::assert::assert;
+
+    let u8_1: u8 = 0u8;
+    let u8_2: u8 = 255u8;
+
+    let u16_1 = u16::from(u8_1);
+    let u16_2 = u16::from(u8_2);
+
+    assert(u16_1 == 0u16);
+    assert(u16_2 == 255u16);
+}
+
 #[test]
 fn test_u16_try_from_u32() {
     use ::assert::assert;