Add CA bundle as file

[steled]

Description of the feature you would like to add / User story

As a user
I would like to be able to add the caBundle as a file
in order to keep the kubeone.yaml file clean.

Solution details

• in kubeone.yaml I can reference the caBundle as a file like: caBundle.pem

Alternative approaches

Use cases

The use case is to keep the kubeone.yaml more clear.
Currently we need to reference the caBundle as string:

apiVersion: kubeone.k8c.io/v1beta2
kind: KubeOneCluster
name: testCluster

versions:
  kubernetes: '1.31.5'

<SUPPRESSED>

caBundle: |
  ##
  ## Bundle of CA Root Certificates
  ##
  ## Certificate data from Mozilla as of: Tue Dec 31 04:12:05 2024 GMT
  ##
  ## Find updated versions here: https://curl.se/docs/caextract.html
  ##
  ## This is a bundle of X.509 certificates of public Certificate Authorities
  ## (CA). These were automatically extracted from Mozilla's root certificates
  ## file (certdata.txt).  This file can be found in the mozilla source tree:
  ## https://hg.mozilla.org/releases/mozilla-release/raw-file/default/security/nss/lib/ckfw/builtins/certdata.txt
  ##
  ## It contains the certificates in PEM format and therefore
  ## can be directly used with curl / libcurl / php_curl, or with
  ## an Apache+mod_ssl webserver for SSL client authentication.
  ## Just configure this file as the SSLCACertificateFile.
  ##
  ## Conversion done with mk-ca-bundle.pl version 1.29.
  ## SHA256: c99d6d3f8d3d4e47719ba2b648992f5b58b150128d3aca3c05c566d8dc98e116
  ##
  
  
  GlobalSign Root CA
  ==================
  -----BEGIN CERTIFICATE-----
  MIIDdTCCAl2gAwIBAgILBAAAAAABFUtaw5QwDQYJKoZIhvcNAQEFBQAwVzELMAkGA1UEBhMCQkUx
  GTAXBgNVBAoTEEdsb2JhbFNpZ24gbnYtc2ExEDAOBgNVBAsTB1Jvb3QgQ0ExGzAZBgNVBAMTEkds
  b2JhbFNpZ24gUm9vdCBDQTAeFw05ODA5MDExMjAwMDBaFw0yODAxMjgxMjAwMDBaMFcxCzAJBgNV
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  THAHoT0KMM0VjU/43dSMUBUc71DuxC73/OlS8pF94G3VNTCOXkNz8kHp1Wrjsok6Vjk4bwY8iGlb
  Kk3Fp1S4bInMm/k8yuX9ifUSPJJ4ltbcdG6TRGHRjcdGsnUOhugZitVtbNV4FpWi6cgKOOvyJBNP
  c1STE4U6G7weNLWLBYy5d4ux2x8gkasJU26Qzns3dLlwR5EiUWMWea6xrkEmCMgZK9FGqkjWZCrX
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  HRMBAf8EBTADAQH/MB0GA1UdDgQWBBRge2YaRQ2XyolQL30EzTSo//z9SzANBgkqhkiG9w0BAQUF
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  Y1Ub8rrvrTnhQ7k4o+YviiY776BQVvnGCv04zcQLcFGUl5gE38NflNUVyRRBnMRddWQVDf9VMOyG
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  X4XSQRjbgbMEHMUfpIBvFSDJ3gyICh3WZlXi/EjJKSZp4A==
  -----END CERTIFICATE-----
  
  Entrust.net Premium 2048 Secure Server CA
  =========================================
  -----BEGIN CERTIFICATE-----
  MIIEKjCCAxKgAwIBAgIEOGPe+DANBgkqhkiG9w0BAQUFADCBtDEUMBIGA1UEChMLRW50cnVzdC5u
  ZXQxQDA+BgNVBAsUN3d3dy5lbnRydXN0Lm5ldC9DUFNfMjA0OCBpbmNvcnAuIGJ5IHJlZi4gKGxp
  bWl0cyBsaWFiLikxJTAjBgNVBAsTHChjKSAxOTk5IEVudHJ1c3QubmV0IExpbWl0ZWQxMzAxBgNV
  BAMTKkVudHJ1c3QubmV0IENlcnRpZmljYXRpb24gQXV0aG9yaXR5ICgyMDQ4KTAeFw05OTEyMjQx
  NzUwNTFaFw0yOTA3MjQxNDE1MTJaMIG0MRQwEgYDVQQKEwtFbnRydXN0Lm5ldDFAMD4GA1UECxQ3
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  MCMGA1UECxMcKGMpIDE5OTkgRW50cnVzdC5uZXQgTGltaXRlZDEzMDEGA1UEAxMqRW50cnVzdC5u
  ZXQgQ2VydGlmaWNhdGlvbiBBdXRob3JpdHkgKDIwNDgpMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8A
  MIIBCgKCAQEArU1LqRKGsuqjIAcVFmQqK0vRvwtKTY7tgHalZ7d4QMBzQshowNtTK91euHaYNZOL
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  BAMCAQYwDwYDVR0TAQH/BAUwAwEB/zAdBgNVHQ4EFgQUVeSB0RGAvtiJuQijMfmhJAkWuXAwDQYJ
  KoZIhvcNAQEFBQADggEBADubj1abMOdTmXx6eadNl9cZlZD7Bh/KM3xGY4+WZiT6QBshJ8rmcnPy
  T/4xmf3IDExoU8aAghOY+rat2l098c5u9hURlIIM7j+VrxGrD9cv3h8Dj1csHsm7mhpElesYT6Yf
  zX1XEC+bBAlahLVu2B064dae0Wx5XnkcFMXj0EyTO2U87d89vqbllRrDtRnDvV5bu/8j72gZyxKT
  J1wDLW8w0B62GqzeWvfRqqgnpv55gcR5mTNXuhKwqeBCbJPKVt7+bYQLCIt+jerXmCHG8+c8eS9e
  nNFMFY3h7CI3zJpDC5fcgJCNs2ebb0gIFVbPv/ErfF6adulZkMV8gzURZVE=
  -----END CERTIFICATE-----

<SUPPRESSED>

It would be better and cleaner to just reference to a file:

apiVersion: kubeone.k8c.io/v1beta2
kind: KubeOneCluster
name: testCluster

versions:
  kubernetes: '1.31.5'

<SUPPRESSED>

caBundle: caBundle.pem

Additional information