feat: enhance multiple capabilities file format & fix mixed permissions schema

[amrbashir]

This enhances the DX of defining multiple definitions in a single JSON file, previously the only way was:

{
  "capabilities": [ {...}, {...} ] 
}

now we can also support

[
  {...},
  {...}
]

toml however can't take advantage of this due to the nature of toml but doesn't matter that much

[[capabilities]]
identifier = "id"

[[capabilities]]
identifier = "another-one"

[amrbashir]

This PR also fixes generation of PermissionEntry which made the generated schema not accept the following valid permission array:

{
  "permissions": ["perm1", { "identifier": "perm2" }]
}

Even though mixed permission array are parsed correctly in toml, the Event Better TOML extension in vscode still flags the following tomls as incorrect:

identifier = "allow-http"
windows = ["main"]

[[permissions]]
identifier = "allow-read"

and

identifier = "allow-http"
windows = ["main"]
permissions = ["app:allow-app-hide", { identifier = "allow-read" }]

This maybe a bug in Event Better TOML extension but I am not of aware of any other tool I can use to test and compare

Edit: tried to use taplo-cli to validate the schema and it worked fine, so not sure where the problem is. Anyways, since the format is supported by us and the schema generated is correct, this IDE problem shouldn't concern us.

Edit2: after closing and re-opening vscode, the validation seems to accept it and work fine so maybe after this PR schema fix, users won't have to deal with this at all.

[lucasfernog]

the Even Better TOML extension schema validation isn't perfect, at least autocompletion doesn't always work. That's why we use JSON by default for capabilities.

[lucasfernog]

a change file would be nice here i think

[amrbashir]

Added