Add token exchange grant and update pre-issue access token v2

[Lashen1227]

This pull request introduces to add token exchange grant type and update pre-issue access token version to v2.

OAuth flow enhancements:

• Added support for the "token exchange" grant type in the flows.json configuration, enabling the system to recognize and handle OAuth token exchange flows.

Configuration updates:

• Updated the default version of the pre_issue_access_token action type from v1 to v2 in the server feature configuration, ensuring that the latest implementation is used.

Related PRs:

• Enhance pre-issue access token action to token exchange grant type & pre-issue access token action versioning wso2-extensions/identity-inbound-auth-oauth#3000
• Add audience handling in token request message context wso2-extensions/identity-oauth2-grant-token-exchange#47

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 49.89%. Comparing base (6e1b88e) to head (5df5a87).
⚠️ Report is 214 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7658      +/-   ##
============================================
+ Coverage     49.84%   49.89%   +0.05%     
+ Complexity    19869    18724    -1145     
============================================
  Files          2144     2124      -20     
  Lines        132858   131072    -1786     
  Branches      27664    27393     -271     
============================================
- Hits          66228    65404     -824     
+ Misses        58214    57305     -909     
+ Partials       8416     8363      -53     

Flag	Coverage Δ
unit	35.62% <ø> (-0.01%)	⬇️

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