ftl secret set panics if ftl-project.toml doesnt exist

[mistermoe]

FTL Version: 0.185.4

not sure if ftl-project.toml ends up getting created by default when calling ftl init now but it definitely didn't get created by default in prior versions. might be helpful to create it if it doesn't exist when running this command or any command that necessitates its existence

Repro

❯ ftl secret set plz --envar
Secret:
FTL_SECRET_cGx6=IlwiYWJjZFwiIg
panic: runtime error: index out of range [-1]

goroutine 1 [running]:
github.com/TBD54566975/ftl/common/configuration.ProjectConfigResolver[...].setMapping(0x140003d9170?, {{0x0, 0x140003d9530}, 0x0, {0x0, 0x0, 0x0}, {0x0, 0x0, 0x0}, ...}, ...)
	github.com/TBD54566975/ftl/common/configuration/projectconfig_resolver.go:154 +0x204
github.com/TBD54566975/ftl/common/configuration.ProjectConfigResolver[...].Set(0x103ebcae0?, {0x103eac0d8?, 0x140003fee10?}, {{{0x0, 0x0?}, 0x0?}, {0x14000162040, 0x3}}, 0x14000617a70)
	github.com/TBD54566975/ftl/common/configuration/projectconfig_resolver.go:84 +0x1c0
github.com/TBD54566975/ftl/common/configuration.(*Manager[...]).Set(0x6, {0x103eac0d8?, 0x140003fee10}, {{{0x0, 0x0}, 0x0}, {0x14000162040, 0x3}}, {0x103bfad40, 0x1400032ad20})
	github.com/TBD54566975/ftl/common/configuration/manager.go:132 +0xf0
main.(*secretSetCmd).Run(0x104a8e8e0, {0x103eac0d8, 0x140003fee10}, 0x140004a20e0?, {0x103eb03a0?, 0x104af8300?})
	github.com/TBD54566975/ftl/cmd/ftl/cmd_secret.go:146 +0x2b4
reflect.Value.call({0x103c52580?, 0x104a8e8e0?, 0x140004a1788?}, {0x1038893f1, 0x4}, {0x140006889c0, 0x3, 0x1033a3688?})
	reflect/value.go:596 +0x970
reflect.Value.Call({0x103c52580?, 0x104a8e8e0?, 0x140004a1888?}, {0x140006889c0?, 0x103e8a9e0?, 0x140004a17c0?})
	reflect/value.go:380 +0x94
github.com/alecthomas/kong.callFunction({0x103c52580?, 0x104a8e8e0?, 0x140004a1a10?}, 0x140003fef60)
	github.com/alecthomas/[email protected]/callbacks.go:98 +0x390
github.com/alecthomas/kong.(*Context).RunNode(0x14000599f00, 0x14000499d10, {0x140004a1e78, 0x1, 0x103ecb1f0?})
	github.com/alecthomas/[email protected]/context.go:774 +0x630
github.com/alecthomas/kong.(*Context).Run(0x1400031da70?, {0x140004a1e78?, 0x140003fee10?, 0x103bbd660?})
	github.com/alecthomas/[email protected]/context.go:799 +0x138
main.main()
	github.com/TBD54566975/ftl/cmd/ftl/main.go:130 +0xc68

[alecthomas]

This is actually already fixed in main, just not rolled out yet because of unrelated annoying bugs.