Allow mass update of filters

[TonyGravagno]

This is a variation of the idea in #282 but approaching it differently.

After copying a filters to another profile, we often need to manually change domain names in search terms or the profile name in actions. It can take significant time to do this when many filters are being copied. This can be done more easily with quickFilters, by getting a backup, editing the saved file, then importing the saved JSON. But this isn't user-friendly.

I propose the creation of a new dialog that allows any number of text or regex substitutions for the current or upcoming clone operations.
Examples:

Field	From	To
accountName	"imap:...Foo...."	"imap:...Bar..."
filterName	"Filter 1 for Foo"	"Filter 1 for Bar"
searchTerm.value.str	"Foo"	"Bar"
actionList.targetFolderUri	"imap:...Foo...."	"imap:...Bar..."

The goal is only to do global changes on text, no other functionality.

It would be helpful to be able to save and copy these replacement patterns themselves, as from time to time we want to setup a new account that has the settings of a current account, and it would be painful to have to repeat this process.

As noted in #282 it can be helpful to specify "whatever the new account/profile is, rather than having to detail it here. So in the above example, consider a placeholder for the source and target profile, like $source and $target, which makes the last example above:
actionList.targetFolderUri From "$source" to "$target"

Rather than spending too much time on the UI up front, I'm thinking in alpha a simple textbox can accept the substitutions. If that proves worthwhile then a UI can be added later. But given the size of the audience that might do this and the infrequent need, the text box might just be all that's required. For re-usability we can save our own text blocks wherever we want and paste them in as desired.