Add localhostmasquerade to Thunder plugin

[TeknoVenus]

Description

Add localhostMasquerade functionality to Thunder plugin.

When enabled, Thunder will be available at 127.0.0.1:9998 inside the container in addition to 100.64.11.1:9998. This is useful for applications that don't correctly respect the THUNDER_ACCESS env var.

Refactor some iptables rule generation code for re-use, as localhost masquerade feature is used across Network, AS and Thunder plugins.

Test Procedure

When the Thunder plugin is configured with localhostMasquerade set:

"rdkPlugins": {
        "thunder": {
            "required": true,
            "dependsOn": ["networking"],
            "data": {
                "bearerUrl": "http://localhost",
                "localhostMasquerade": true
            }
        }
    }

Thunder should be accessible over 127.0.0.1:9998 inside the container.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other (doesn't fit into the above categories - e.g. documentation updates)

Requires Bitbake Recipe changes?

• The base Bitbake recipe (meta-rdk-ext/recipes-containers/dobby/dobby.bb) must be modified to support the changes in this PR (beyond updating SRC_REV)

[rdkcmf-jenkins]

Blackduck scan failure details

Summary: 0 violations, 0 files pending approval, 1 file pending identification.

• Protex Server Path: /home/blackduck/github/Dobby/130/rdkcentral/Dobby

• Commit: 0c05053

Report detail: gist

[rdkcmf-jenkins]

WARNING: A Blackduck scan failure has been waived

A prior failure has been upvoted

• Upvote reason: Spurious

• Commit: 0c05053

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[scthunderbolt]

Closed due to inactivity, please restore if still needed.