feat: indicator chart

[jnumainville]

Adds indicator chart for DH-18091
Note that examples might not work correctly because of deephaven/deephaven-core#6547
Here is some working examples

import deephaven.plot.express as dx
from deephaven import agg as agg
from deephaven import time_table

sym_data = time_table("PT1S").update(["Price = randomDouble(0.0, 5.0)", "StartingPrice = 3", "Sym = (i % 2 == 0) ? `DOG` : `DOG`"]).tail(2).sort(["Sym"])

indicator_plot_basic = dx.indicator(sym_data, value="Price", title="DOG")
indicator_plot_delta = dx.indicator(sym_data, value="Price", reference="StartingPrice")
indicator_plot_text = dx.indicator(sym_data, value="Price", reference="StartingPrice", by="Sym", text="Sym")
indicator_plot_styled = dx.indicator(
    sym_data,
    value="Price",
    reference="StartingPrice",
    text="Sym",
    by="Sym",
    gauge="bullet",
    by_vars=("increasing_color", "decreasing_color", "gauge_color"),
    increasing_color_map={"FISH": "lemonchiffon"},
    decreasing_color_map={"FISH": "salmon"},
    gauge_color_map={"FISH": "chartreuse"},
    increasing_text="Up: ",
    decreasing_text="Down: ",
    prefix="$ ",
    suffix=" (USD)",
    number_format="#,##0.00"
)

[mofojed]

Can we also add an e2e test in tests/app.d/express.py?

[mofojed]

This example is kind of confusing. What is the by_vars argument for? Why are we doing a by here at all when we've already filtered the table to one Sym?

[jnumainville]

This is so that the symbol can be specified in the increasing_color_map and decreasing_color_map, although it shouldn't have filtered to one symbol so I'll fix that.

[mofojed]

Might want to have this fix as a separate PR just so it's clear this is fixed in the release notes (is there a ticket for it? When do we run into this issue?)

[mofojed]

Autodoc isn't loving this:

ValueError: Missing documentation for deephaven.plot.express.indicator parameters {"##0.00'"}. Verify that parameter names have leading asterisks in the description.

However you're parsing the args, probably just need to check that the comma is at the end, as it seems to pick up the comma in the string right now. Fix that issue in autodoc in a PR before this PR goes through.

[jnumainville]

Since I'm removing this default this won't block here, but I'll open another ticket because that needs to be solved eventually.

[mofojed]

I kind of want an = at the end just to denote the end of the "prefix".

[jnumainville]

done

[jnumainville]

I have added some new changes, especially with regards to number format and title. I still need to add unit and e2e tests for these new changes.

This PR is blocked on deephaven/web-client-ui#2352 as well.