MQTT Startup Refactoring Part 1: core/ packages part 1 (#1728)

This PR specifically introduces a `core` folder and moves the following packages over, without any other changes:

- `api/backend`
- `api/config`
- `api/options`
- `api/schema`

Once this is merged and we confirm there's no regressions, I can migrate over the remaining changes piece by piece to split up application startup, backend services, http, and mqtt as was the goal of the earlier PRs!

api/config/prediction.go

@@ -1,50 +0,0 @@
-package api_config
-
-type PredictionOptions struct {
-
-	// Also part of the OpenAI official spec
-	Model string `json:"model" yaml:"model"`
-
-	// Also part of the OpenAI official spec
-	Language string `json:"language"`
-
-	// Also part of the OpenAI official spec. use it for returning multiple results
-	N int `json:"n"`
-
-	// Common options between all the API calls, part of the OpenAI spec
-	TopP        float64 `json:"top_p" yaml:"top_p"`
-	TopK        int     `json:"top_k" yaml:"top_k"`
-	Temperature float64 `json:"temperature" yaml:"temperature"`
-	Maxtokens   int     `json:"max_tokens" yaml:"max_tokens"`
-	Echo        bool    `json:"echo"`
-
-	// Custom parameters - not present in the OpenAI API
-	Batch         int     `json:"batch" yaml:"batch"`
-	F16           bool    `json:"f16" yaml:"f16"`
-	IgnoreEOS     bool    `json:"ignore_eos" yaml:"ignore_eos"`
-	RepeatPenalty float64 `json:"repeat_penalty" yaml:"repeat_penalty"`
-	Keep          int     `json:"n_keep" yaml:"n_keep"`
-
-	MirostatETA float64 `json:"mirostat_eta" yaml:"mirostat_eta"`
-	MirostatTAU float64 `json:"mirostat_tau" yaml:"mirostat_tau"`
-	Mirostat    int     `json:"mirostat" yaml:"mirostat"`
-
-	FrequencyPenalty float64 `json:"frequency_penalty" yaml:"frequency_penalty"`
-	TFZ              float64 `json:"tfz" yaml:"tfz"`
-
-	TypicalP float64 `json:"typical_p" yaml:"typical_p"`
-	Seed     int     `json:"seed" yaml:"seed"`
-
-	NegativePrompt      string  `json:"negative_prompt" yaml:"negative_prompt"`
-	RopeFreqBase        float32 `json:"rope_freq_base" yaml:"rope_freq_base"`
-	RopeFreqScale       float32 `json:"rope_freq_scale" yaml:"rope_freq_scale"`
-	NegativePromptScale float32 `json:"negative_prompt_scale" yaml:"negative_prompt_scale"`
-	// AutoGPTQ
-	UseFastTokenizer bool `json:"use_fast_tokenizer" yaml:"use_fast_tokenizer"`
-
-	// Diffusers
-	ClipSkip int `json:"clip_skip" yaml:"clip_skip"`
-
-	// RWKV (?)
-	Tokenizer string `json:"tokenizer" yaml:"tokenizer"`
-}