Fix/route query type 3566

[yash-dayama]

Fixes #3566

Updated typedef of interface Route from:
query: Dictionary<string | (string | null)[]>
to:
query: Dictionary<string | null | (string | null)[]>

Changes made:

1. Updated TypeScript type definition to properly handle null values in query parameters
2. Updated Flow type definitions to match the TypeScript changes
3. Added dedicated type tests in types/test/query-types.test.ts that verify:
   • String values (?foo=bar)
   • Null values (?foo)
   • Array values (?foo=bar&foo=baz)
   • Mixed arrays with both strings and nulls

This change ensures proper typing for query parameters that don't have any value, while maintaining backward compatibility.

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[yash-dayama]

After 3 retries here is what I have done @posva can you please have a look

Fixed the Route query type definition issue with the following changes:

1. Type Definitions:
   - Updated Route interface query type to properly handle null values:
     ```ts
     query: Dictionary<string | null | (string | null)[]>
     ```
   - Added QueryValue and QueryDictionary types in Flow for better type organization
   - Added dedicated type tests in types/test/query-types.test.ts

2. Runtime Changes:
   - Improved isObjectEqual to properly handle array comparisons and string conversions
   - Updated resolveQuery and stringifyQuery to use QueryDictionary type
   - Fixed query type handling in normalizeLocation

These changes ensure proper typing for all query parameter scenarios:
- String values (?foo=bar)
- Null values (?foo)
- Array values (?foo=bar&foo=baz)
- Mixed arrays with both strings and nulls

All tests are passing and Flow type checking is successful. This maintains backward compatibility while fixing the type definition issues reported in #3566.

[posva]

Thanks but same as in the other PR 😅