resource/certificate_settings: Multiple bug fixes

[gdavison]

Description

Fixes multiple bugs in certificate_settings:

• Prevent permanent diff when certificate_settings not set.
• Prevent ValidationException when setting certificate_settings.type to AMPLIFY_MANAGED.
• Prevent "unexpected state" error when setting certificate_settings.type to CUSTOM.
• No longer ignores changes to certificate_settings when updating.
• Prevents panic in some circumstances when certificate_settings is not set during update.

Relations

Closes #38387
Closes #39890

Output from Acceptance Testing

% make testacc PKG=amplify TESTS='TestAccAmplify_serial/DomainAssociation'

--- PASS: TestAccAmplify_serial (3851.69s)
    --- PASS: TestAccAmplify_serial/DomainAssociation (3851.69s)
        --- PASS: TestAccAmplify_serial/DomainAssociation/certificateSettings_Custom (1327.02s)
        --- PASS: TestAccAmplify_serial/DomainAssociation/disappears (296.65s)
        --- PASS: TestAccAmplify_serial/DomainAssociation/update (812.72s)
        --- PASS: TestAccAmplify_serial/DomainAssociation/basic (297.96s)
        --- PASS: TestAccAmplify_serial/DomainAssociation/certificateSettings_Managed (1117.31s)

[github-actions]

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[ewbankkit]

LGTM 🚀.

% AMPLIFY_DOMAIN_NAME=terraform-provider-aws-acctest-acm.com make testacc TESTARGS='-run=TestAccAmplify_serial/^DomainAssociation$$' PKG=amplify
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go1.23.3 test ./internal/service/amplify/... -v -count 1 -parallel 20  -run=TestAccAmplify_serial/^DomainAssociation$ -timeout 360m
2024/12/17 08:17:43 Initializing Terraform AWS Provider...
=== RUN   TestAccAmplify_serial
=== PAUSE TestAccAmplify_serial
=== CONT  TestAccAmplify_serial
=== RUN   TestAccAmplify_serial/DomainAssociation
=== RUN   TestAccAmplify_serial/DomainAssociation/disappears
=== RUN   TestAccAmplify_serial/DomainAssociation/update
=== RUN   TestAccAmplify_serial/DomainAssociation/basic
=== RUN   TestAccAmplify_serial/DomainAssociation/certificateSettings_Managed
=== RUN   TestAccAmplify_serial/DomainAssociation/certificateSettings_Custom
--- PASS: TestAccAmplify_serial (3446.23s)
    --- PASS: TestAccAmplify_serial/DomainAssociation (3446.23s)
        --- PASS: TestAccAmplify_serial/DomainAssociation/disappears (310.86s)
        --- PASS: TestAccAmplify_serial/DomainAssociation/update (740.27s)
        --- PASS: TestAccAmplify_serial/DomainAssociation/basic (301.51s)
        --- PASS: TestAccAmplify_serial/DomainAssociation/certificateSettings_Managed (1185.50s)
        --- PASS: TestAccAmplify_serial/DomainAssociation/certificateSettings_Custom (908.09s)
PASS
ok  	github.com/hashicorp/terraform-provider-aws/internal/service/amplify	3451.937s

[github-actions]

This functionality has been released in v5.82.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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