Add CLI instruction to transfer an authority

[fedgiac]

Add a path for the CLI to transfer an authority. This is specifically to transfer solver management to the solver team.

I also isolated the code that reads a keypair from a file or uses a default, since it's reused in the solver command and will be used again in the future. I also gave it a separate folder for future new commands.

How to test

Manually try on devnet that the authority gets changed as expected.

Example.

I decoded the account data before and after execution. Note that the second word of the account was changed, as expected for reclaim-authority.

$ cow authority transfer --keypair ../deployer.json  reclaim-authority 11111111111111111111111111111111 
   signature = qhUqBvQFstjhh4m4JJ92YNMe7TYxRnT6PoTeYgowR5ZqaHeGF5EbzK8PxnCmKRocF1WDpQwihXWwpRSBVw8q68E
        role = ReclaimAuthority
newAuthority = 11111111111111111111111111111111
      signer = B6acm3swJK9pJ7fe4i4GQgP7x5A3RndvsdV2bKhcA1i5
    statePda = 9t7yR5UvhuQvApxSqsZFL7wxqq4u78DAkQQhxKxMxkJt
$ solana account 9t7yR5UvhuQvApxSqsZFL7wxqq4u78DAkQQhxKxMxkJt

Public Key: 9t7yR5UvhuQvApxSqsZFL7wxqq4u78DAkQQhxKxMxkJt
Balance: 0.001143 SOL
Owner: C7PXyLpLQBh3Ce7e9DNj3rDVUvwqa5orDwQG5hs1rfNi
Executable: false
Rent Epoch: 18446744073709551615
Length: 97 (0x61) bytes
0000:   81 96 02 c8  9d 9b 92 0a  c1 bc d7 ae  14 49 64 12   .............Id.
0010:   b3 df f8 4a  83 dc 36 7a  83 82 da c4  88 8a 8b 1d   ...J..6z........
0020:   66 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00   f...............
0030:   00 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00   ................
0040:   00 96 02 c8  9d 9b 92 0a  c1 bc d7 ae  14 49 64 12   .............Id.
0050:   b3 df f8 4a  83 dc 36 7a  83 82 da c4  88 8a 8b 1d   ...J..6z........
0060:   66                                                   f

$ cow authority transfer --keypair ../deployer.json  reclaim-authority B6acm3swJK9pJ7fe4i4GQgP7x5A3RndvsdV2bKhcA1i5
   signature = 2LirnCqmBuyPAdmG8YZb68v6nPiLN5ipQRTig3yTaxgr8HJ8vbzSzWA922d9uTnUpqfk4DCe8GFL6zMMmxCWvy2s
        role = ReclaimAuthority
newAuthority = B6acm3swJK9pJ7fe4i4GQgP7x5A3RndvsdV2bKhcA1i5
      signer = B6acm3swJK9pJ7fe4i4GQgP7x5A3RndvsdV2bKhcA1i5
    statePda = 9t7yR5UvhuQvApxSqsZFL7wxqq4u78DAkQQhxKxMxkJt
$ solana account 9t7yR5UvhuQvApxSqsZFL7wxqq4u78DAkQQhxKxMxkJt

Public Key: 9t7yR5UvhuQvApxSqsZFL7wxqq4u78DAkQQhxKxMxkJt
Balance: 0.001143 SOL
Owner: C7PXyLpLQBh3Ce7e9DNj3rDVUvwqa5orDwQG5hs1rfNi
Executable: false
Rent Epoch: 18446744073709551615
Length: 97 (0x61) bytes
0000:   81 96 02 c8  9d 9b 92 0a  c1 bc d7 ae  14 49 64 12   .............Id.
0010:   b3 df f8 4a  83 dc 36 7a  83 82 da c4  88 8a 8b 1d   ...J..6z........
0020:   66 96 02 c8  9d 9b 92 0a  c1 bc d7 ae  14 49 64 12   f............Id.
0030:   b3 df f8 4a  83 dc 36 7a  83 82 da c4  88 8a 8b 1d   ...J..6z........
0040:   66 96 02 c8  9d 9b 92 0a  c1 bc d7 ae  14 49 64 12   f............Id.
0050:   b3 df f8 4a  83 dc 36 7a  83 82 da c4  88 8a 8b 1d   ...J..6z........
0060:   66                                                   f

[linear-code]

SC-417

[kaze-cow]

beauty