DM-48445: Replace ScriptTemplates with Jinja Template

[tcjennings]

Removes ScriptTemplates from the application.

Does not deprecate or remove APIs related to ScriptTemplates, but eliminates the use of ScriptTemplates from both seed (example) files and script-generation functions and methods.

The concept of "script templates" is refactored using Jinja template files with "snippets" enabled or disabled based on configuration flags, e.g., "wms: htcondor" enables a template block that switches on the value of wms. In this way, a single template file can be considered, updated, and rendered according to the specific needs of a campaign instead of pulling in multiple template snippets from the database.

This pattern is also used in the process of writing a bash script to submit to htcondor for execution, with a simplified approach to setting up a "condor" or a "panda" stack environment and without the extra steps concerning clobbering and reimplementing environment variables in the shebang.

[ctslater]

Looks great.

[ctslater]

The only potential pitfall I see here is that wms seems to come from some deep down plumbing, so I could imagine that going missing somehow and then the script fails in a very confusing way. I don't know if there's a good way to guard against that, since wms=None might also be valid in some cases?

[tcjennings]

For now I'll use the class attribute from the WmsMethodEnum which is otherwise unused. This will promote the value from being part of a "specblock" to being part of the actual Handler instance used for the script, so it should always be both available and set correctly.