Feature: ECC Support in TPM2

Changes and Additions

Adjust copyrights for funding attribution (that's why so many files are changed...).
Analogously to RSA, an EC Adapter module is added which allows to manage, load and use* TPM2 EC Keys.
Redundant logic of the RSA Adapter also used by the EC Adapter is generalized to TPM2::Signature_Operation and TPM2::Verification_Operation in tpm2_pkops.h.
Augmentation of the TPM2 Crypto Backend to support ECDH key exchange in order to allow for authenticated sessions with TPM2 EC keys.
Disentanglement of the Crypto Backend from the Adapters: Before, the Backend required the TPM2 RSA Adapter to establish a session via a TPM2 RSA key. Now, the backend RSA/ECDH functionalities require only the corresponding Botan software RSA/ECDH modules. (These are not requirements of the backend module though - they are only required if one wants to establish a session with a key of the respective type).
More defensive input checks in Crypto Backend.

As PK Ops of EC keys this PR only supports ECDSA Signing/Verification. Other types such as ECSchnorr and SM2 are not supported.
Particularly, ECDH Key Agreement in Botan with a TPM2 EC key is not yet supported. This is more involved since a TPM EC key may be used for ECDSA/ECDH/..., which is more of an operation as opposed to a key (ECDSA or ECDH ) in Botan. Note that this is not to be confused with ECDH for the Crypto Backend used for the sessions with any EC TPM2 key, which is supported (see above).
Only NIST curves are supported since 25519/448 and Brainpool are not yet supported by tpm2-tss.