Validate: add ability to expand src validate commands for future health check functionality (#921)

* Refactor validate functionality into pkg

To support expansion of the validate command, the current validate
functionality will need to be moved to a new subcommand.

* Use existing internal api package for graphql requests
* Remove create first admin features
* Refactor configuration structs to support multiple code hosts in future
* Add cool emoji to output
* Add insight test cleanup

* Add env vars for Github access token

Github access token is needed for new validate command. Add token to config.

* Add 'src validate install' command

* Move 'src validate' functionality into 'srv validate install' commmand to allow for
more validate subcommands.

* Change validation API to be more specific

* Change SRC_GITHUB_TOKEN to only be read if needed for command

* Update CHANGELOG.md

* Add warning if SRC_GITHUB_TOKEN isn't set

* An auth token is required for code hosts when using `src validate install`, warn user and exit if not set.

* Remove unused deps

* Separate tasks being performed

* Add symbol search to default queries

* Change default queries to use sourcegraph/src-cli repo instead of gorilla/mux

Author: jdpleiness

CHANGELOG.md

@@ -14,11 +14,15 @@ All notable changes to `src-cli` are documented in this file.
 ### Added
 
 - `src validate` has an added check to determine if an instance is able to create a basic code insight. [#912](https://github.com/sourcegraph/src-cli/pull/912)
+- Add visual feedback to `src validate install` CLI [#921](https://github.com/sourcegraph/src-cli/pull/921)
+- Add insight cleanup as per [#912](https://github.com/sourcegraph/src-cli/pull/912#issuecomment-1377084768)
 
 ### Changed
 
 - Renamed `src users clean` command to `src users prune` [#901](https://github.com/sourcegraph/src-cli/pull/901)
 - Failed code-intel uploads now print every error encountered while retrying instead of only the error encountered in the final retry attempt. [#46281](https://github.com/sourcegraph/sourcegraph/pull/46281)
+- `src validate` has been changed to `srv validate install` subcommand [#921](https://github.com/sourcegraph/src-cli/pull/921)
+- Move GitHub token for `srv validate` to ENV var [#921](https://github.com/sourcegraph/src-cli/pull/921)
 
 ### Fixed
 
@@ -28,6 +32,8 @@ All notable changes to `src-cli` are documented in this file.
 
 ### Removed
 
+- Removed __create first admin__ feature from `src validate` [#921](https://github.com/sourcegraph/src-cli/pull/921)
+
 ## 4.3.0
 
 ### Added