Update golangci-lint-action to v7 and add nil TED handling

[watal]

Description

• Updated golangci-lint-action to version v7 in the CI workflow.
• Improved error handling of file and connection closures (for golangci-lint-action@v7).
• Refactored code to use tagged switch statements (for golangci-lint-action@v7).
• Handled nil TED and GoBGP update channel.
• Added new PCEP object types.

Type of change

• Refactoring

Motivation and Context

• The golangci-lint-action update ensures compatibility with the latest version.
• Added error handling for nil TED and GoBGP update channels. (Ref. Handling when TED is nil #26)
• The addition of new PCEP object types, which is needed for future protocol implementations.