Enhancement: Enhance NFunction evaluation and support advanced NFunctions (#2577)

# Description

Enhance NFunction sanitization and support advanced functions:
- Start page counting from 1 rather than 0 as PDFs are one based from
the user's perspective, thus functions results would be affected by
starting with "0" rather than "1".
- Ignore out of bound results rather than stopping iterations to work
with functions such as (n - 4) when page count is 10 as we would get
positive values when n > 4.
- Remove spaces to support expressions such as 2n + 1 rather just 2n+1.
- Support advanced functions as follows:
- Support expressions such as follows 5(n-1), n(n-1), expressions
followed by opening rounded without '*' operator.
- Support expressions such as follows (n-1)5, (n-1)n, expressions
preceded closing rounded without '*' operator.
- Support consecutive "n" expressions, examples: nnn, 2nn, nn*3, nnnn.

Closes #(issue_number)

## Checklist

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have performed a self-review of my own code
- [ ] I have attached images of the change if it is UI based
- [x] I have commented my code, particularly in hard-to-understand areas
- [ ] If my code has heavily changed functionality I have updated
relevant docs on [Stirling-PDFs doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
- [x] My changes generate no new warnings
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

cucumber/features/general.feature

@@ -1,7 +1,7 @@
 @general
 Feature: API Validation
 
-	
+
   @split-pdf-by-sections @positive
   Scenario Outline: split-pdf-by-sections with different parameters
     Given I generate a PDF file as "fileInput"
@@ -66,7 +66,7 @@ Feature: API Validation
     | pageNumbers | file_count |
     | 1,3,5-9     | 8          |
     | all         | 20         |
-    | 2n+1        | 11         |
+    | 2n+1        | 10         |
     | 3n          | 7          |
 
 
@@ -106,9 +106,9 @@ Feature: API Validation
 	And the response ZIP should contain 2 files
     And the response file should have size greater than 0
 	And the response status code should be 200
-	
+
 	Examples:
-    | format | 
-    | png        | 
+    | format |
+    | png        |
     | gif         |
-    | jpeg        | 
+    | jpeg        |