Issue #, if available:: N/A

Description of changes:

• When you user q settings --help, the delete option help says "Delete a value" when it should be delete a key as delete does not take value.
• Going by Usage as mentioned in q settings --help, when you type out q settings -d chat.defaultAgent "some-value" The error message shown is confusing and contradictory. It prints out two contradicting statement. As seen below

dev-dsk-fast-chownira-2c-402b637c % q settings --delete chat.defaultAgent my-preferred-agent
error: the argument '--delete' cannot be used with '[VALUE]'

Usage: q settings --delete <KEY> [VALUE] <--- this contradicts above

For more information, try '--help'.

• Fixed both the above problems, now by mistake if user uses value in delete , it will print a user friendly correcting message

dev-dsk-fast-chownira-2c-402b637c % cargo run --bin chat_cli -- settings -d chat.defaultAgent "some-val"
   Compiling chat_cli v1.16.3 (/local/home/chownira/AmazonQ/amazon-q-developer-cli/crates/chat-cli)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 43.75s
     Running `target/debug/chat_cli settings -d chat.defaultAgent some-val`
error: the argument '--delete' cannot be used with '[VALUE]'
 Usage: q settings --delete chat.defaultAgent

testing

Wrote a unit test and
Ran

• cargo test
• cargo clippy
• cargo +nightly fmt

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