build: generate drivers with std lib only [skip ci]

[burningalchemist]

This pull request refactors the drivers_gen.go code generation script to remove its dependency on the github.com/dave/jennifer/jen library, making the tool more self-contained and robust. It also improves usability by providing clearer usage instructions, more flexible argument handling, and deterministic output.

Dependency removal and code generation:

• Removed the dependency on the github.com/dave/jennifer/jen code generation library; now generates Go source code using the standard library and formats it with go/format. (drivers_gen.go, Makefile) [1] [2]

Usability improvements:

• Enhanced argument handling to accept both os.Args[2:] and os.Args[1:], improving compatibility and flexibility in how the script is invoked. (drivers_gen.go)
• Added a usage message that lists available driver keys if no arguments are provided, improving user guidance. (drivers_gen.go)
• Outputs the list of selected drivers and the output filename, giving users clearer feedback on what the script is doing. (drivers_gen.go)

Output stability:

• Ensures deterministic and de-duplicated ordering of imported drivers in the generated file, making builds more reproducible. (drivers_gen.go)