[Feature Request] MISE supports certificate in PEM format on NET 6+

[luz1115]

Is your feature request related to a problem? Please describe.
Received exception when loading token decryption certificate from Keyvault, with MISE migration:
'Microsoft.IdentityModel.S2S.Configuration.S2SAuthenticationManagerFactory' caught exceptions when loading the certificate. Exception : 'IDW10701: Only PKCS #12 content type is supported. Found Content-Type: application/x-pem-file. '

solution is at NET 6.0

Describe the solution you'd like
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Please support PEM formatted certificate with MISE migration.

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[jmprieur]

The fix should be done here:

microsoft-identity-web/src/Microsoft.Identity.Web.Certificate/KeyVaultCertificateLoader.cs

Line 96 in e528daa

if (CertificateConstants.MediaTypePksc12.Equals(secret.Properties.ContentType, StringComparison.OrdinalIgnoreCase))

if (secret .Value.Properties.ContentType == "application/x-pem-file")
{
   cert = X509Certificate2.CreateFromPem(secret.Value, secret.Value);
}