feat: add the option to enable HTTP/2 option for function apps

[MacMur85]

Description

Adding the http2_enabled configuration option for Function Apps to enable the HTTP/2.
Currently set to true for development and sandbox, false for all other environments.

Major benefits of implementing HTTP/2 are:

• improved performance,
• enhanced security,
• reduced latency

Context

More information on the HTTP/2 itself available here.
A quick TL;DR:

HTTP/2 is a rework of how HTTP semantics flow over TCP connections, and HTTP/2 support is present in Windows 10 and Windows Server 2016. 
HTTP/2 is a major upgrade after nearly two decades of HTTP/1.1 use and reduces the impact of latency and connection load on web servers.

The major advance of HTTP/1.1 was the use of persistent connections to service multiple requests in a row. In HTTP/2, a persistent connection can be used to service multiple simultaneous requests.
In the process, HTTP/2 introduces several additional features that improve the efficiency of HTTP over the network.

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

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Sensitive Information Declaration

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• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.

[github-actions]

Unit Test Results

✔️ Tests 777 / 777 - passed in 63.5s
📝 Coverage 56.94%
📏 4285 / 7411 lines covered 🌿 1055 / 1968 branches covered
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✏️ updated for commit 2612617

[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

See analysis details on SonarQube Cloud