SCIM filter operators (AND, OR, NOT) are case-sensitive

[JayaShakthi97]

Describe the issue: The logical gate operators are case-sensitive. This leads to unexpected behavior when filtering users, where only the left part of the expression is taken into consideration if we use AND in all-caps, for example.

As per the SCIM API specification [1]:

"Attribute names and attribute operators used in filters are case insensitive."

How to reproduce: Here is a quick summary of how to reproduce:

1. Setup an Identity Server instance and add the configuration below to the <IS_HOME>/repository/conf/deployment.toml file:

[scim2_multi_attribute_filtering]
use_pagination = "true"

3. Go to the Claim Configuration page (Claims > List > http://wso2.org/claims), uncheck the 'Read only' checkbox for the 'Department' claim and enable 'Supported by Default' for the 'Account Locked' claim.
4. In the PRIMARY user store, create:

• 2 users with 'Account Locked' set to 'true' and 'Department' set to '123'
• 1 user with 'Account Locked' set to 'true' and 'Department' set to '456'

6. Run the cURL command below:

curl --location --request GET 'https://localhost:9443/scim2/Users?filter=urn%3Aietf%3Aparams%3Ascim%3Aschemas%3Aextension%3Aenterprise%3A2.0%3AUser%3AaccountLocked%20eq%20%22true%22%20AND%20urn%3Aietf%3Aparams%3Ascim%3Aschemas%3Aextension%3Aenterprise%3A2.0%3AUser%3Adepartment%20eq%20%22123%22' \
--header 'Authorization: Basic ******'

7. Notice how there are 3 results rather than 2.

[1] https://datatracker.ietf.org/doc/html/draft-ietf-scim-api-13#section-3.2.2.2