Handle missing TCP upstreams as warnings (#8461)

[ashishb-solo]

• Handle missing TCP upstreams as warnings

• Move changelog to new location

• Fix a broken test

• Apply suggestions from code review

• Fix error in changelog

• Address nil safety issue on TcpHostError

• Fix nil safety check

• Address a few review comments

• Update projects/gloo/api/grpc/validation/gloo_validation.proto

• Populate ErrorLevel for TcpHostWarning

• Mark InvalidDestinationError as deprecated

• Add some stricter error checking

• Move duplicated code into a reusable function

• Codegen

• Fix an error from refactor

• Use the ErrorWithKnownLevel interface to switch on error report types

• Handle the case where tcp host num is not provided

• Provide a separate Context object to carry additional information

Earlier commits simply added more fields to the ErrorWithKnownLevel interface to aid in providing the necessary information required to report the error. This commit is an attempt to break that out into a separate object so additional fields do not need to be added every time more contextual information is needed to correctly report the error

• Add docstrings on exported types

• Adding changelog file to new location

• Deleting changelog file from old location

• Adding changelog file to new location

• Deleting changelog file from old location

• Clean up hard-coded warning type

Previously, we were just using InvalidDestinationWarning for all warning types

• we remove that now and use a switch statement to use the right kind

• Fix an inaccurate comment

---

Description

Please include a summary of the changes.

This bug fixes ... \ This new feature can be used to ...

Context

Users ran into this bug doing ... \ Users needed this feature to ...

Checklist:

• I included a concise, user-facing changelog (for details, see https://github.com/solo-io/go-utils/tree/main/changelogutils) which references the issue that is resolved.
• If I updated APIs (our protos) or helm values, I ran make -B install-go-tools generated-code to ensure there will be no code diff
• I followed guidelines laid out in the Gloo Edge contribution guide
• I opened a draft PR or added the work in progress label if my PR is not ready for review
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

BOT NOTES:
resolves https://github.com/solo-io/solo-projects/issues/5163

[solo-changelog-bot]

Issues linked to changelog:
https://github.com/solo-io/solo-projects/issues/5163