finalize migration to OAuth 2.0 Attestation-Based Client Authentication

[peppelinux]

It is required to consolidate the adoption of OAuth 2.0 Attestation-Based Client Authentication

here: https://github.com/italia/eudi-wallet-it-docs/blob/versione-corrente/docs/en/pid-eaa-issuance.rst?plain=1#L98C1-L98C17 https://github.com/italia/eudi-wallet-it-docs/blob/versione-corrente/docs/en/pid-eaa-issuance.rst?plain=1#L125C1-L125C21

please remove this client_assertion_type since it is already in the POST request https://github.com/italia/eudi-wallet-it-docs/blob/versione-corrente/docs/en/pid-eaa-issuance.rst?plain=1#L162C1-L162C99

here add an example of $WIA~$WIA-PoP https://github.com/italia/eudi-wallet-it-docs/blob/versione-corrente/docs/en/pid-eaa-issuance.rst?plain=1#L254C23-L254C42

here https://github.com/italia/eudi-wallet-it-docs/blob/versione-corrente/docs/en/pid-eaa-issuance.rst?plain=1#L396 https://github.com/italia/eudi-wallet-it-docs/blob/versione-corrente/docs/en/pid-eaa-issuance.rst?plain=1#L594

[peppelinux]

This issues when resolved will resolve also the following issues:

• https://github.com/italia/eudi-wallet-it-docs/issues/130
• https://github.com/italia/eudi-wallet-it-docs/issues/33