feat: update string/base TypeScript declarations

PR-URL: #8132

Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>
Signed-off-by: stdlib-bot <82920195+stdlib-bot@users.noreply.github.com>

Author: stdlib-bot

lib/node_modules/@stdlib/string/base/docs/types/index.d.ts

@@ -68,6 +68,9 @@ import reverseCodePoints = require( '@stdlib/string/base/reverse-code-points' );
 import reverseGraphemeClusters = require( '@stdlib/string/base/reverse-grapheme-clusters' );
 import rpad = require( '@stdlib/string/base/right-pad' );
 import rtrim = require( '@stdlib/string/base/right-trim' );
+import slice = require( '@stdlib/string/base/slice' );
+import sliceCodePoints = require( '@stdlib/string/base/slice-code-points' );
+import sliceGraphemeClusters = require( '@stdlib/string/base/slice-grapheme-clusters' );
 import snakecase = require( '@stdlib/string/base/snakecase' );
 import startcase = require( '@stdlib/string/base/startcase' );
 import startsWith = require( '@stdlib/string/base/starts-with' );
@@ -1083,7 +1086,7 @@ interface Namespace {
 	*
 	* @example
 	* var out = ns.replaceBefore( 'Hello World!', '', 'foo', 0 );
-	* // returns 'Hello World!'
+	* // returns 'Hello world!'
 	*
 	* @example
 	* var out = ns.replaceBefore( 'Hello World!', 'xyz', 'foo', 0 );
@@ -1272,6 +1275,81 @@ interface Namespace {
 	*/
 	rtrim: typeof rtrim;
 
+	/**
+	* Slices UTF-16 code units from a string.
+	*
+	* @param str - input string
+	* @param start - slice start index (inclusive)
+	* @param end - slice end index (exclusive)
+	* @returns output string
+	*
+	* @example
+	* var out = ns.slice( 'last man standing', 1, 17 );
+	* // returns 'ast man standing'
+	*
+	* @example
+	* var out = ns.slice( 'presidential election', 1, 21 );
+	* // returns 'residential election'
+	*
+	* @example
+	* var out = ns.slice( 'JavaScript', 4, 10 );
+	* // returns 'Script'
+	*
+	* @example
+	* var out = ns.slice( 'Hidden Treasures', 0, 6 );
+	* // returns 'Hidden'
+	*
+	* @example
+	* var out = ns.slice( 'foo bar', 2, 7 );
+	* // returns 'ar'
+	*
+	* @example
+	* var out = ns.slice( 'foo bar', -1, 7 );
+	* // returns 'r'
+	*/
+	slice: typeof slice;
+
+	/**
+	* Slices a string based on Unicode code point indices.
+	*
+	* @param str - input string
+	* @param start - the `ith` Unicode code point to start a slice (inclusive)
+	* @param end - the `jth` Unicode code point to end a slice (exclusive)
+	* @returns output string
+	*
+	* @example
+	* var out = ns.sliceCodePoints( 'Hello 👋 World', 1, 3 );
+	* // returns 'el'
+	*
+	* @example
+	* var out = ns.sliceCodePoints( '👋👋👋', 1, 2 );
+	* // returns '👋'
+	*/
+	sliceCodePoints: typeof sliceCodePoints;
+
+	/**
+	* Slices a string based on grapheme cluster (i.e., user-perceived character) indices.
+	*
+	* @param str - input string
+	* @param start - the `ith` grapheme cluster to start a slice (inclusive)
+	* @param end - the `jth` grapheme cluster to end a slice (exclusive)
+	* @returns output string
+	*
+	* @example
+	* var out = ns.sliceGraphemeClusters( 'Hello World', 0, 5 );
+	* // returns 'Hello'
+	*
+	* out = ns.sliceGraphemeClusters( '👋👋👋', 0, 2 );
+	* // returns '👋👋'
+	*
+	* out = ns.sliceGraphemeClusters( 'अनुच्छेद', 1, 3 );
+	* // returns 'नुच्'
+	*
+	* out = ns.sliceGraphemeClusters( 'Hello World', -5, -1 );
+	* // returns 'Worl'
+	*/
+	sliceGraphemeClusters: typeof sliceGraphemeClusters;
+
 	/**
 	* Converts a string to snake case.
 	*