[cmd] Enable db-manager CLI to support subcommands

[mickmis]

This PR refactors the db-manager command to support subcommands (notably for #1116).

• The existing db-manager logic is now defined as the migration subcommand. Various updates of scripts, deployment files, and documentations are made in that regard.
• Introduce use of spf13/cobra and spf13/pflag libraries to support this.
• Note that not all flags are migrated to using spf13/pflag, however the existing ones that use flag are still supported (notably for the cockroachdb flags).
• go mod tidy was ran.
• The diff is unfortunately not very readable, however here is a change overview that should help review:
  • cmds/db-manager/main.go is a new file
  • cmds/db-manager/main.go was moved to cmds/db-manager/migration/migration.go and adapted:
    • panics are replaced by returning errors
    • flags are defined with spf13/pflag
    • context is passed from parent
    • check for parameter schemas_dir is replaced by use of function MarkFlagRequired

[BenjaminPelletier]

It is annoying when git doesn't recognize a move + edit. When that is known to be coming, the move can be done in the first commit (updating references, etc as necessary) and then the changes can be done in a second commit so reviewers can look at the changes separately from the move. But not worth doing for this PR, I think.

[mickmis]

It is annoying when git doesn't recognize a move + edit. When that is known to be coming, the move can be done in the first commit (updating references, etc as necessary) and then the changes can be done in a second commit so reviewers can look at the changes separately from the move. But not worth doing for this PR, I think.

Indeed, I've not thought about it, thanks for the tip. Ended up doing it in this PR it was fast enough.