openapi: Better mount points for kv-v1 and kv-v2 in openapi.json

[averche]

@maxb discovered an issue in hashicorp/vault-client-go#187 (comment) with the existing generated openapi.json: the generated mount path parameters for kv-v1 and kv-v2 are "kv" and "secret" respectively, which are not very intuitive when translated into generated code.

This PR fixes the issue by explicitly mounting kv-v1 at "kv-v1/" and kv-v2 and "kv-v2/" which results in proper mount paths in the generated opneapi.json:

cat scripts/openapi.json | jq -c '.paths | to_entries[] | .key as $key | .value | to_entries[] | select(.key == "get" or .key == "post" or .key == "list" or .key == "delete") | [$key, .key, .value.operationId]' | grep kv-v1
["/{kv_v1_mount_path}/{path}","get","kv-v1-read"]
["/{kv_v1_mount_path}/{path}","post","kv-v1-write"]
["/{kv_v1_mount_path}/{path}","delete","kv-v1-delete"]

cat scripts/openapi.json | jq -c '.paths | to_entries[] | .key as $key | .value | to_entries[] | select(.key == "get" or .key == "post" or .key == "list" or .key == "delete") | [$key, .key, .value.operationId]' | grep kv-v2
["/{kv_v2_mount_path}/config","get","kv-v2-read-configuration"]
["/{kv_v2_mount_path}/config","post","kv-v2-configure"]
["/{kv_v2_mount_path}/data/{path}","get","kv-v2-read"]
["/{kv_v2_mount_path}/data/{path}","post","kv-v2-write"]
["/{kv_v2_mount_path}/data/{path}","delete","kv-v2-delete"]
["/{kv_v2_mount_path}/delete/{path}","post","kv-v2-delete-versions"]
["/{kv_v2_mount_path}/destroy/{path}","post","kv-v2-destroy-versions"]
["/{kv_v2_mount_path}/metadata/{path}","get","kv-v2-read-metadata"]
["/{kv_v2_mount_path}/metadata/{path}","post","kv-v2-write-metadata"]
["/{kv_v2_mount_path}/metadata/{path}","delete","kv-v2-delete-metadata"]
["/{kv_v2_mount_path}/subkeys/{path}","get","kv-v2-read-subkeys"]
["/{kv_v2_mount_path}/undelete/{path}","post","kv-v2-undelete-versions"]