Searching functions with parenthesis returns no results for valid funtion names

[blobaugh]

When using the code reference search form at ​https://developer.wordpress.org/reference/ for functions by name with and without the parenthesis changes the results.

For example, searching for 'sanitize_text_field()' will return zero results
​https://developer.wordpress.org/?s=sanitize_text_field%28%29&post_type[]=wp-parser-function&post_type[]=wp-parser-hook&post_type[]=wp-parser-class&post_type[]=wp-parser-method

While searching for 'sanitize_text_field' returns multiple results
​https://developer.wordpress.org/?s=sanitize_text_field&post_type[]=wp-parser-function&post_type[]=wp-parser-hook&post_type[]=wp-parser-class&post_type[]=wp-parser-method

Searching with the () should return the function and searching without () should return both the function and the hook.

[coffee2code]

In 951:

Code Reference: presume an exact match search request for a function or method if search term ends with '()'. Fixes #686

Falls back to general search if no exact match found.