feat: Allow specifying SSL/TLS protocol version for FTP-TLS connections.

[HviorForgeFlow]

This change introduces support for implicit FTPS connections in the FTPFileSystem. Previously, only explicit FTPS was supported.

A new parameter security tls has been added to the FTPFileSystem constructor. This parameter allows users to specify the SSL/TLS protocol to be used for implicit FTPS connections,
such as TLSv1.2.

Key changes:

• Introduced ImplicitFTPTLS class to handle automatic SSL wrapping for implicit FTPS.
• Added security tls parameter to FTPFileSystem to allow selection of SSL/TLS protocols (e.g., "tlsv1_2").
• Updated the connection logic to differentiate between explicit and implicit FTPS based on the security tls parameter.

This enhancement provides greater flexibility and compatibility for connecting to various FTP servers requiring implicit FTPS with specific security protocols.

[martindurant]

Thank you for contributing. I expect to be able to look through this shortly.

[martindurant]

This all looks very nice - thank you.

One question: why have the extra argument, when we already have one (tls=). Since the existing one is bool, it could still allow for all the str options you are adding here.

[HviorForgeFlow]

Hello @martindurant in this apporach I just was ensuring not to break the current implementation, and yes it makes sense to reuse, I'm going to do a proposal here: 541f7f4

I will squash the commits if we move it forward

[martindurant]

We normally squash-merge anyway, so don't worry about that. This is ready for me to look at again?

[HviorForgeFlow]

Comment attended, ready to review.

[martindurant]

All looks good. I have one request for you to consider.

[HviorForgeFlow]

Looks like the workflow approval got rejected when I squash + force push the commits.
Added a read check on the same test method.

[martindurant]

I believe approval is required every time if you are not already a contributor. For future reference, we squash-merge in this repo anyway, so no need to consolidate your commits in the PR branch.