Refactoring ahead of tg caching fix - pt 1

[erikfuller]

What type of PR is this?
cleanup

Which issue does this PR fix:
This PR includes basic readability improvements, including refactoring of large methods, more descriptive naming for variables and functions, and consistency in imports. There should be NO FUNCTIONAL CHANGES in this PR.

One thing I would like to get feedback on are the contents of the Developer Cheat Sheet.

What does this PR do / Why do we need it:
This is part of a larger refactor which will ultimately remove the lattice data store, specifically for target groups.

Testing done on this change:

└─[$] <git:(refactor-1*)> [laptop] make presubmit
pkg/deploy/lattice/listener_synthesizer.go
New file modification detected in the Git working tree. Please check in before commit.
  - pkg/deploy/lattice/listener_synthesizer.go
?   	github.com/aws/aws-application-networking-k8s/pkg/apis/applicationnetworking/v1alpha1	[no test files]
ok  	github.com/aws/aws-application-networking-k8s/pkg/aws	0.585s	coverage: 24.2% of statements
ok  	github.com/aws/aws-application-networking-k8s/pkg/aws/services	1.121s	coverage: 9.7% of statements
ok  	github.com/aws/aws-application-networking-k8s/pkg/config	1.052s	coverage: 32.9% of statements
ok  	github.com/aws/aws-application-networking-k8s/pkg/deploy	2.609s	coverage: 19.4% of statements
ok  	github.com/aws/aws-application-networking-k8s/pkg/deploy/externaldns	1.613s	coverage: 75.6% of statements
?   	github.com/aws/aws-application-networking-k8s/pkg/k8s	[no test files]
?   	github.com/aws/aws-application-networking-k8s/pkg/model/lattice	[no test files]
?   	github.com/aws/aws-application-networking-k8s/pkg/runtime	[no test files]
?   	github.com/aws/aws-application-networking-k8s/pkg/utils	[no test files]
?   	github.com/aws/aws-application-networking-k8s/pkg/utils/gwlog	[no test files]
?   	github.com/aws/aws-application-networking-k8s/pkg/utils/retry	[no test files]
?   	github.com/aws/aws-application-networking-k8s/pkg/utils/ttime	[no test files]
ok  	github.com/aws/aws-application-networking-k8s/pkg/deploy/lattice	3.399s	coverage: 85.0% of statements
ok  	github.com/aws/aws-application-networking-k8s/pkg/gateway	5.200s	coverage: 77.8% of statements
ok  	github.com/aws/aws-application-networking-k8s/pkg/latticestore	5.289s	coverage: 64.1% of statements
ok  	github.com/aws/aws-application-networking-k8s/pkg/model/core	6.379s	coverage: 61.7% of statements
ok  	github.com/aws/aws-application-networking-k8s/pkg/model/core/graph	6.412s	coverage: 17.2% of statements
ok  	github.com/aws/aws-application-networking-k8s/controllers	1.406s	coverage: 0.0% of statements
ok  	github.com/aws/aws-application-networking-k8s/controllers/eventhandlers	2.106s	coverage: 53.5% of statements

Automation added to e2e:
No changes

Will this PR introduce any new dependencies?:
No

Will this break upgrades or downgrades. Has updating a running cluster been tested?:
n/a

Does this PR introduce any user-facing change?:
No

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[erikfuller]

Please make sure you agree with what's in here

[mikhail-aws]

nice, an easy read

[mikhail-aws]

Not sure that all the changes have to be in same PR, but looks ok.

[coveralls]

Pull Request Test Coverage Report for Build 6397137956

• 281 of 599 (46.91%) changed or added relevant lines in 29 files are covered.
• 14 unchanged lines in 9 files lost coverage.
• Overall coverage decreased (-0.01%) to 46.013%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/deploy/lattice/targets_synthesizer.go	1	2	50.0%
pkg/gateway/model_build_listener.go	8	9	88.89%
pkg/deploy/lattice/service_network_synthesizer.go	4	6	66.67%
pkg/gateway/model_build_targets.go	5	7	71.43%
pkg/model/core/route.go	0	2	0.0%
pkg/deploy/lattice/listener_manager.go	4	7	57.14%
pkg/deploy/lattice/service_network_manager.go	18	21	85.71%
pkg/deploy/lattice/rule_manager.go	15	19	78.95%
pkg/deploy/lattice/target_group_manager.go	26	31	83.87%
pkg/deploy/stack_deployer.go	0	5	0.0%

Files with Coverage Reduction	New Missed Lines	%
controllers/gatewayclass_controller.go	1	0.0%
controllers/gateway_controller.go	1	0.0%
controllers/route_controller.go	1	0.0%
pkg/gateway/model_build_listener.go	1	74.73%
pkg/gateway/model_build_rule.go	1	82.82%
controllers/pod_controller.go	2	0.0%
controllers/service_controller.go	2	0.0%
controllers/serviceexport_controller.go	2	0.0%
controllers/serviceimport_controller.go	3	0.0%

Totals
Change from base Build 6355409430:	-0.01%
Covered Lines:	3855
Relevant Lines:	8378

---

💛 - Coveralls