🐛 Fix aliases in pros v5

[mayankpatibandla]

Summary:

pros v5 set-variable and pros v5 read-variable are explicitly named and pros v5 set_variable and pros v5 read_variable are added as aliases.

Motivation:

The aliases for pros v5 set-variable and pros v5 read-variable are not working. #307 upgraded click which converts underscores in command names to dashes.

Test Plan:

• pros v5 set-variable
• pros v5 set_variable
• pros v5 sv
• pros v5 set
• pros v5 read-variable
• pros v5 read_variable
• pros v5 rv
• pros v5 get

[ayushuk]

LGTM