Add support for serving via HTTPS

[tbell83]

Support serving the code-server via HTTPS when passing in SSL_CERT and SSL_KEY, otherwise maintain current behavior.

Description:

Modify the run script to pass values from environment variables SSL_CERT and SSL_KEY to options --cert and --cert-key respectively, as per the man page:

  --cert                         Path to certificate. If the path is omitted,
                                 both this and --cert-key will be generated.
  --cert-key                     Path to the certificate's key if one was
                                 provided.

If both environment variables are not set, code-server will run HTTP, as is the current behavior.

Benefits of this PR and context:

Support serving via HTTPS.

How Has This Been Tested?

Run with both variables defined, code-server runs HTTPS
Run without both variables defined, code server runs HTTP

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/code-server/2.1698-pkg-475182b4-pr-25/index.html
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/code-server/2.1698-pkg-475182b4-pr-25/shellcheck-result.xml

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/code-server/2.1698-pkg-475182b4-pr-25/index.html
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/code-server/2.1698-pkg-475182b4-pr-25/shellcheck-result.xml

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/code-server/2.1698-pkg-475182b4-pr-25/index.html
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/code-server/2.1698-pkg-475182b4-pr-25/shellcheck-result.xml

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/code-server/2.1698-pkg-475182b4-pr-25/index.html
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/code-server/2.1698-pkg-475182b4-pr-25/shellcheck-result.xml

[tbell83]

Dupes #23

[aborniak]

So , when this pull request will be merged into the master branch ?