Move configuration to yaml format

[javanlacerda]

Contribute towards #1111

Summary

Migrate the configuration file from json to yaml.
It also removes the fulcio-config.yaml file that isn't used. (I've double checked it by running the docker-compose. It worked fine)
It concentrate the issuers and meta-issuers in a single file that can be found at config/identity/config.yaml
It also removes the https://auth-staging.eclipse.org/realms/sigstore from the list of issuers, as it is unavailable.
It is necessary to improve the onboarding for new OIDC providers, and make it easier to migrate the CI providers to the new generic logic that has been developed here #1679

cc @haydentherapper

Release Note

Documentation

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 50.42%. Comparing base (cf238ac) to head (0c20cf0).
Report is 140 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1720      +/-   ##
==========================================
- Coverage   57.93%   50.42%   -7.52%     
==========================================
  Files          50       70      +20     
  Lines        3119     4121    +1002     
==========================================
+ Hits         1807     2078     +271     
- Misses       1154     1814     +660     
- Partials      158      229      +71     

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[haydentherapper]

Some suggestions:

• Have a single config.yaml file which contains all of the trusted providers
• Remove config/fulcio-config.yaml, double checking that it's not used
• Add the email and description to the configuration struct
• Omit email/description when outputting configuration via API

[javanlacerda]

Some suggestions:

• Have a single config.yaml file which contains all of the trusted providers
• Remove config/fulcio-config.yaml, double checking that it's not used
• Add the email and description to the configuration struct
• Omit email/description when outputting configuration via API

Thank you for the suggestions. I managed to address the two first in this PR and I intend to address the other two in a next PR. WDYT?

[haydentherapper]

Can you update the documentation for

fulcio/docs/oidc.md

Line 14 in 1a404b1

* Add the new issuer to the [configuration](https://github.com/sigstore/fulcio/blob/main/config/fulcio-config.yaml) by running `go run federation/main.go`

and

fulcio/tools/loadtest/README.md

Line 27 in 1a404b1

To fetch a certificate, you will need an OIDC token from one of the [OIDC issuers](https://github.com/sigstore/fulcio/blob/main/config/fulcio-config.yaml). One way is to fetch a token from Google. Note that you will need to install [`gcloud`](https://cloud.google.com/sdk/gcloud) and create a service account. A service account is necessary for the `--include-email` flag, which is needed to get an OIDC token with the correct format for Fulcio.

to update references to the deleted yaml?

[haydentherapper]

@cpanato can you review the updates around CI?

[javanlacerda]

Can you update the documentation for

fulcio/docs/oidc.md

Line 14 in 1a404b1

* Add the new issuer to the [configuration](https://github.com/sigstore/fulcio/blob/main/config/fulcio-config.yaml) by running `go run federation/main.go`

and

fulcio/tools/loadtest/README.md

Line 27 in 1a404b1

To fetch a certificate, you will need an OIDC token from one of the [OIDC issuers](https://github.com/sigstore/fulcio/blob/main/config/fulcio-config.yaml). One way is to fetch a token from Google. Note that you will need to install [`gcloud`](https://cloud.google.com/sdk/gcloud) and create a service account. A service account is necessary for the `--include-email` flag, which is needed to get an OIDC token with the correct format for Fulcio.

to update references to the deleted yaml?

Done! I will address the other doc updates in the PR removing the federation stuff. make sense?

[haydentherapper]

Thanks! Will merge Monday if there's no more comments.