crypto/tls: expose implemented cipher suites

[noneymous]

Allows to dynamically retrieve a list of available cipher suites. This change allows a variety of applicatoins:

• Enable all available ciphers programmatically, without hardcoding, and always refering to the latest set of implemented ciphers
• Filter ciphers by desired flags and use them dynamically, without hardcoding, and always refering to the latest set of implemented ciphers
• Build application configs for user-decided selection of ciphers to allow

Ciphers are returned as copies, in order to avoid messing up internal stuff.

In contrast to the already discussed solutions, this one reduced the amount of necessary changes. Maintainability will be equal to before. This should not contain any breaking changes, as it only makes former private variables public, respectively, adds functions.

Fixes #30325 and #21167

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[agnivade]

Seems like this is the same as #30739. Closing this.