Remove OwnedLiteral and SharedLiteral

From my GitHub searches and from looking at reverse dependencies, it
seems like no one is using these. Further, it seems weird to have these
type declarations for `Literal` but not for any other specific `*Lit`
types. Very often, specific types are used. Removing these slightly
reduces the API area, helping with learnability.

Author: LukasKalbertodt

src/lib.rs

@@ -157,17 +157,10 @@ pub use self::{
 // ===== `Literal` and type defs
 // ==============================================================================================
 
-/// A literal which owns the underlying buffer.
-pub type OwnedLiteral = Literal<String>;
-
-/// A literal whose underlying buffer is borrowed.
-pub type SharedLiteral<'a> = Literal<&'a str>;
-
 /// A literal. This is the main type of this library.
 ///
 /// This type is generic over the underlying buffer `B`, which can be `&str` or
-/// `String`. There are two useful type aliases: [`OwnedLiteral`] and
-/// [`SharedLiteral`].
+/// `String`.
 ///
 /// To create this type, you have to either call [`Literal::parse`] with an
 /// input string or use the `From<_>` impls of this type. The impls are only
@@ -243,7 +236,7 @@ impl<B: Buffer> Literal<B> {
 impl Literal<&str> {
     /// Makes a copy of the underlying buffer and returns the owned version of
     /// `Self`.
-    pub fn into_owned(self) -> OwnedLiteral {
+    pub fn into_owned(self) -> Literal<String> {
         match self {
             Literal::Bool(l) => Literal::Bool(l.to_owned()),
             Literal::Integer(l) => Literal::Integer(l.to_owned()),