router_check: read routes from bootstrap config

[cainelli]

Commit Message: router_check: read routes from bootstrap config Additional Description: Support reading from bootstrap configuration and load runtime flags.

Risk Level: Low Testing:

# bootstrap config
router_check_tool --bootstrap-config test/tools/router_check/test/config/ClusterHeaderBootstrap.yaml --test-path test/tools/router_check/test/config/ClusterHeaderBootstrap.golden.proto.json -l main

# router config
router_check_tool --config-path test/tools/router_check/test/config/ClusterHeader.yaml --test-path test/tools/router_check/test/config/ClusterHeader.golden.proto.json

Fixes https://github.com/envoyproxy/envoy/issues/35174

[repokitteh-read-only[bot]]

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:cat:

Caused by: https://github.com/envoyproxy/envoy/pull/35662 was opened by cainelli.

see: more, trace.

[cainelli]

@adisuissa I also did a small refactor with options (sorry to increase the scope) let me know if it makes sense to keep or if you'd prefer to have as a separate PR . I must also add more tests but before would like to know if this high level approach with separate flag for bootstrap makes sense or you'd prefer a single flag for config, if yes I'd appreciate any pointer how I could do it. see https://github.com/envoyproxy/envoy/pull/35662#discussion_r1716080661

[phlax]

@cainelli needs a main merge

/wait

[ravenblackx]

@adisuissa ping-nag

[ravenblackx]

@adisuissa promised to followup on PRs today, but it looks likely to slip to another (business) day.

[cainelli]

Thank you for following-up @ravenblackx and no worries, I understand and am patience. I appreciate the hard work from all Envoy maintainers :). Please let me know if I can make this any easier to review @adisuissa.

[kyessenov]

/wait-any

[tyxia]

/wait

Per discussion thread https://github.com/envoyproxy/envoy/pull/35662#discussion_r1794234910, this pr seems to be waiting for the action from the author.

[cainelli]

To be followed-up with a new PR. https://github.com/envoyproxy/envoy/pull/35662#discussion_r1801379721