Miniscript - Add Literal Boolean Operators

[odudex]

In another finding from the Bitcoinfuzz project by @brunoerg, we learned that, unlike Core and Rust Miniscript, Embit won't parse booleans, 0 and 1, as arguments for logical operators like and_v. Currently, a miniscript like "wsh(and_v(v:0,and_v(v:0,0)))" raises an error: Unknown operator '0,and_v'.

This PR aims to enable Embit to properly load and compile boolean literals by implementing the JustZero and JustOne miniscript objects and refactoring the parsing algorithm.
Although booleans have little or no use in practical miniscripts, being able to parse them is important for standardizing behavior across different miniscript implementations.

Kudos to @brunoerg and @erickcestari for pointing the issue.
Thanks @jdlcdl for the guidance through all the process, from understanding the issue, the code, and for the multiple reviews.

Note: A second issue involving the recursive depth limit in the Fuzz test case remains, even after resolving the boolean support, and will not be covered by this PR.

[odudex]

The commits from this pull request have now been merged into Embit's develop branch.