Co-Author: @silverwind @wxiaoguang 
Replace: #24404

See:
- [defining configuration variables for multiple
workflows](https://docs.github.com/en/actions/learn-github-actions/variables#defining-configuration-variables-for-multiple-workflows)
- [vars
context](https://docs.github.com/en/actions/learn-github-actions/contexts#vars-context)

Related to:
- [x] protocol: https://gitea.com/gitea/actions-proto-def/pulls/7
- [x] act_runner: https://gitea.com/gitea/act_runner/pulls/157
- [x] act: https://gitea.com/gitea/act/pulls/43

#### Screenshoot
Create Variable:

![image](https://user-images.githubusercontent.com/33891828/236758288-032b7f64-44e7-48ea-b07d-de8b8b0e3729.png)


![image](https://user-images.githubusercontent.com/33891828/236758174-5203f64c-1d0e-4737-a5b0-62061dee86f8.png)

Workflow:
```yaml
  test_vars:
    runs-on: ubuntu-latest
    steps:
      - name: Print Custom Variables
        run: echo "${{ vars.test_key }}"
      - name: Try to print a non-exist var
        run: echo "${{ vars.NON_EXIST_VAR }}"
```

Actions Log:

![image](https://user-images.githubusercontent.com/33891828/236759075-af0c5950-368d-4758-a8ac-47a96e43b6e2.png)

---
This PR just implement the org / user (depends on the owner of the
current repository) and repo level variables, The Environment level
variables have not been implemented.
Because
[Environment](https://docs.github.com/en/actions/deployment/targeting-different-environments/using-environments-for-deployment#about-environments)
is a module separate from `Actions`. Maybe it would be better to create
a new PR to do it.

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Giteabot <teabot@gitea.io>

This PR moves the secrets and runners settings to actions settings on
all settings(repo,org,user,admin) levels.

After this PR, if
[ENABLED](5e7543fcf4/custom/conf/app.example.ini (L2604))
inside `app.ini` under `[actions]` is set to `false`, the "Actions" tab
(including runners management and secrets management) will not be shown.

After, the settings under actions settings for each level:

1. Admin Level
"Runners Management"
<img width="1437" alt="Screen Shot 2023-04-26 at 14 34 20"
src="https://user-images.githubusercontent.com/17645053/234489731-15822d21-38e1-4560-8bbe-69f122376abc.png">

2. User Level
"Secrets Management"
<img width="1427" alt="Screen Shot 2023-04-26 at 14 34 30"
src="https://user-images.githubusercontent.com/17645053/234489795-68c9c0cb-24f8-4f09-95c6-458ab914c313.png">

3. Repo and Organization Levels
"Runners Management" and "Secrets Management" 
   Org:
<img width="1437" alt="Screen Shot 2023-04-26 at 14 35 07"
src="https://user-images.githubusercontent.com/17645053/234489996-f3af5ebb-d354-46ca-9087-a0b586845281.png">

<img width="1433" alt="Screen Shot 2023-04-26 at 14 35 14"
src="https://user-images.githubusercontent.com/17645053/234490004-3abf8fed-81fd-4ce2-837a-935dade1793d.png">

    Repo:
<img width="1419" alt="Screen Shot 2023-04-26 at 14 34 50"
src="https://user-images.githubusercontent.com/17645053/234489904-80c11038-4b58-462c-9d0b-8b7cf70bc2b3.png">
    
<img width="1430" alt="Screen Shot 2023-04-26 at 14 34 57"
src="https://user-images.githubusercontent.com/17645053/234489918-4e8d1fe2-9bcd-4d8a-96c1-238a8088d92e.png">

It also finished these tasks :

- [x] rename routers function "runners" to "actions", and refactor
related file names
- [x] check and modify part of the runners related functions to match
their name
- [x] Fix backend check caused by fmt check

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>